A Simple Riddle You Probably Will Get Wrong. The Watermelon Paradox!

No video

A Simple Riddle You Probably Will Get Wrong. The Watermelon Paradox!

Рет қаралды 163,099

Күн бұрын

Even people who have PhDs in science get this simple brain teaser wrong! Can you figure it out? (It is also known as the potato paradox.)
References
www.fiitjeedwa...
blog.cambridge...
en.wikipedia.o...
graphicmaths.c...
en.wikipedia.o...
Subscribe: www.youtube.co...
Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas!
If you purchase through these links, I may be compensated for purchases made on Amazon. As an Amazon Associate I earn from qualifying purchases. This does not affect the price you pay.
If you purchase through these links, I may be compensated for purchases made on Amazon. As an Amazon Associate I earn from qualifying purchases. This does not affect the price you pay.
Book ratings are from January 2023.
My Books (worldwide links)
mindyourdecisi...
My Books (US links)
Mind Your Decisions: Five Book Compilation
amzn.to/2pbJ4wR
A collection of 5 books:
"The Joy of Game Theory" rated 4.3/5 stars on 290 reviews
amzn.to/1uQvA20
"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" rated 4.1/5 stars on 33 reviews
amzn.to/1o3FaAg
"40 Paradoxes in Logic, Probability, and Game Theory" rated 4.2/5 stars on 54 reviews
amzn.to/1LOCI4U
"The Best Mental Math Tricks" rated 4.3/5 stars on 116 reviews
amzn.to/18maAdo
"Multiply Numbers By Drawing Lines" rated 4.4/5 stars on 37 reviews
amzn.to/XRm7M4
Mind Your Puzzles: Collection Of Volumes 1 To 3
amzn.to/2mMdrJr
A collection of 3 books:
"Math Puzzles Volume 1" rated 4.4/5 stars on 112 reviews
amzn.to/1GhUUSH
"Math Puzzles Volume 2" rated 4.2/5 stars on 33 reviews
amzn.to/1NKbyCs
"Math Puzzles Volume 3" rated 4.2/5 stars on 29 reviews
amzn.to/1NKbGlp
2017 Shorty Awards Nominee. Mind Your Decisions was nominated in the STEM category (Science, Technology, Engineering, and Math) along with eventual winner Bill Nye; finalists Adam Savage, Dr. Sandra Lee, Simone Giertz, Tim Peake, Unbox Therapy; and other nominees Elon Musk, Gizmoslip, Hope Jahren, Life Noggin, and Nerdwriter.
My Blog
mindyourdecisi...
Twitter
/ preshtalwalkar
Instagram
/ preshtalwalkar
Merch
teespring.com/...
Patreon
/ mindyourdecisions
Press
mindyourdecisi...

Пікірлер: 862

@matthewedwards9423 Ай бұрын

This sounds more like someone trying to come up with an excuse for why they ate half the melons on the train.

@micahlong2073 Ай бұрын

But only the water!

@mayukhintesarislam306 23 күн бұрын

lmao

@fmarten0 12 күн бұрын

True

@viniviper2973 2 күн бұрын

Very good

@NetherFX Ай бұрын

❌i've done half my tasks ✅my performance went from 99% to 98%

@HxTurtle Ай бұрын

not the same statement, though.

@TheTrueM4gg0t 21 күн бұрын

Not quite. Like this: ❌ Boss, I sleep only 98% of the time on the job now, instead of 99%! ✅ Boss, I doubled the amount of work I complete every day, I need a pay raise! 💸

@kubastachu9860 20 күн бұрын

@@HxTurtle yeah, more like "I'm doing less than half the work but only lost 1% of performance, yikes!" followed by "but why do you let me go with such good stats? Lost trust? How am I not dependable enough to not assign those tasks?"

@jonathanodude6660 3 күн бұрын

@@kubastachu9860 eh a clearer explanation is assuming that the workload halved from 100 tasks to 50, and they went from doing 99 / 100 tasks to doing 49 / 50 tasks. their total task count has to change for this to make any sense.

@PeterFrancisFernandez Ай бұрын

The false assumption is that there is a 1% loss of water versus the original weight, when in fact it is only a ratio. Using that it becomes easier to understand that youre trying then to work out what weight fits the new ratio rather than thinking of it as having lost 1% of water

@TheOreoOverlord Ай бұрын

Yup, once understanding this, the problem becomes much more simple and obvious. Took me some time though because it's worded(quite well) to lead you to believe the % is not a ratio but rather an ammount

@Christopher._M Ай бұрын

I knew it felt like I was missing something when it first thought about it. Which is why I was sure you would have to solve algebraically to get it but it's such an easy assumption and mistakes to make if you just read it

@senseibear2436 Ай бұрын

Somebody is cheating here with the wording! I could have sworn the video said 99% of the total weight (100kg) was water.... Or is that what the listener just infers themselves, hence the riddle? It just sounds like the person removed 1.01% of the total weight...

@stevemaurer8120 Ай бұрын

It's not a "false assumption". It's an incorrectly specified problem. And that's the real answer: "As specified, this question is too ambiguous to solve".

@brevitygreaves2321 Ай бұрын

"dropped to 98%" means what? Is there an actual 1kg watermelon anywhere in the world such that, upon extracting 1% of its water content, its weight magically drops to 50% of its original weight?

@Ynook Ай бұрын

The way I see it basically what you did in the end. If 1 Kg of watermelon is now 2% of the weight, the total weight is 50 times 1 Kg.

@theglobalwarming6081 Ай бұрын

I solved this myself. I am both confused how much weight was lost but also it kinda made sense

@scottmcmillen3015 Ай бұрын

Your method is far more intuitive to me than the ones Presh started with. First notice that 1%, hence 1 kg, is not water. For 98% water, we ask: “1 kg is 2% of what?” This question gives the intuitive answer 50 kg, or can be translated into the equation 1 = .02x, and hence x = 50 kg.

@ModelLights Ай бұрын

@@theglobalwarming6081 'I am both confused how much weight was lost ' Realize, there's an easier way to see the reduction in weight, take it further. 1kg solid and 99kg water gets the 99% water content. But to get to 50% water content, you have to have the starting 1kg solid, and only 1kg water left. You have to lose 98kg of the initial 99kg to get down to 50% water content. The water content percentage being referenced to the 1kg solids instead of an independent reference means the scale slides, and by using 1%/99% to start, the scale slides very hard. 99 kg of water is 26.12137 gallons. Take five 5 gallon buckets of water and another gallon, put them together, and try to wrap it all and hold it together with only 1kg of watermelon skin and rind. It's a not real problem, specifically chosen to use the self referencing 'water content' with an unrealistically high water content to generate the huge swing in values. It could work in some less familiar things, but you would be hard pressed to do this with a watermelon. Real watermelons tend to be 4% or so solid, they'll be mush before you get to 1%.

@michaelallen1432 Ай бұрын

That's pretty much what I did. The water is the thing that changes and it's the unknown. But the mass of everything else is the same before and after. You start with 100kg total, 99% of which is water. So everything else is 1kg. The amount after, is still 1kg. You are told that the water content drops to 98%. So that means the percent of everything else is 2% Knowing that the amount of everything but the water is 1kg, and that the percentage of it is 2% , you can then calculate the total mass of everything as 1kg/0.02 = 50kg

@beepbop6697 Ай бұрын

@@ModelLightsfrom what I'm reading, watermelons are 92% water. Perhaps if you remove the inedible green rind then the editable red stuff is 96% water...

@PugganBacklund Ай бұрын

my mind went: melon went from 1% -> 2%, doubeling, so weight must be half. then i started think, what did i miss..

@vt2788 Ай бұрын

You are just genetically superior

@southernbreeze3278 Ай бұрын

didn't make sense to me 'till I read this comment

@emad3241 Ай бұрын

you got lucky

@marvhollingworth663 Ай бұрын

You missed nowt, that makes perfect sense.

@user-jc2lz6jb2e Ай бұрын

You focused on what WASN'T water, yet the water is the focus of the question (all the information is in terms of it). People think "oh 99% to 98% isn't much loss", and that's where they get tripped up.

@budsellers Ай бұрын

Your math solution is correct, but that freight shipping cost will be wasted because the load of watermelons are useless now

@martinprince8253 Ай бұрын

Watermelons that are twice as sweet? gimme gimme gimme

@dirkbester9050 Ай бұрын

Not at all. You can still make watermelon skin jam from it, and the concentrated watermelon juice can be drinkable. If it is not some kind of maidenless pit free melon, you can plant the seeds next year. Unless it also rotted. That would leave you with making some watermelon wine or vinegar at best.

@wideeyedraven15 Ай бұрын

They are not useless.

@angrytedtalks Ай бұрын

Bowling balls.

@adb012 Ай бұрын

The watermelons will not be dry. They are still 98% water. And they will be twice as sweet and flavorful.

@theoroth6515 Ай бұрын

From 6:26 to 7:07, there is the expression "d=0.1(100)=1" but it should be "d=0.01(100)=1"

@k1ry4n Ай бұрын

If the non-water content goes from 1 (1% of the original mass) to 2% of the new mass it means that we lost half of the original mass. If 1 kg now is 2% the new mass is 50 kg.

@aidanhammer6968 Ай бұрын

This is a much clearer way of framing it.

@k1ry4n Ай бұрын

@@aidanhammer6968 The explanation in the video seems to me unnecessarily complicated.

@SigFigNewton 29 күн бұрын

Wow. Nice! I wrote out three very simple equations with three variables and did the algebra

@SigFigNewton 29 күн бұрын

Looks like the video basically did what I did. U making me feel foolish

@ExtraTrstl 19 күн бұрын

This helped, thank you!

@mickdavies5647 Ай бұрын

They are students at a barbecue. I can think of several reasons why they got the answer wrong, ranging from 4.5% to 40% in volume 😂

@cparks1000000 Ай бұрын

😂😂😂 Some even 65%.

@TitularHeroine Ай бұрын

😂😂

@hedgehogclaws8877 Ай бұрын

This was actually hilarious

@jimmyh2137 28 күн бұрын

I can thing of some other reasons. More... plant based, let's say.

@wild_insomnia Ай бұрын

damn,but it's headscratching how flabby dried out potatoes can still consist of 98% water...That's something surreal...

@jensraab2902 Ай бұрын

To be honest, a "potato" containing 99% or even "only" 98% of water wouldn't be much of a potato. Even watermelons, according to Auntie Google, don't consist of 99% water. The figures I found on the quick was 92% water in a watermelon, and 80% in a potato.

@beepbop6697 Ай бұрын

... And adult human male is 60% water

@tomdekler9280 Ай бұрын

@@beepbop6697 Well yeah, both give a big wet splat when you chuck them out of a 12th story window.

@9_1.1 Ай бұрын

simple explanation: assuming the non-water part of the melons didnt change, that part is still 1kg. that 1kg is now 2% of the total mass, or 1/50th, meaning the rest is 49/50ths, or 49kgs.

@Xenon.O Ай бұрын

You can't just assume that 99% of the watermelon's "content" is the same as 99% of its weight. I don't know why they keep making their questions' wording difficult to understand.

@sheshakrishna1111 Ай бұрын

Chemical Engineers: Material Balance....

@sauerjoseph Ай бұрын

Yes, as a fellow ChemE, I was thinking the same thing. This is what we do every day. No decent ChemE should ever get this wrong! We know from experience how much minor changes in %concentration can make such a huge change in lbs total removed. Presh could have plotted an X-Y chart of "Change in total weight" VS "Starting %Water" (1% drop in %Water at each point) and use this to show how this 'change in total weight' heavily depends on the starting %Water.

@educassus Ай бұрын

I came here to say the same. Before becoming a ChemE, I solved problems like this using cross multiplication when I was studying for my technical level degree in Chem.

@shivanshukantprasad Ай бұрын

Calling veridical paradox a paradox itself feels like a veridical paradox.

@M1412B Ай бұрын

In the Netherlands this problem was presented about 20 years ago on a national IQ test TV show as a stallholder selling 200kg of cucumbers on a hot day. I remember being stunned by the answer as it is so counter intuitive.

@MichaelPiz Ай бұрын

But how old is the driver?

@isambo400 Ай бұрын

And how freshly does his toad walk?

@Bob94390 Ай бұрын

Because he has neither a fish.

@dirkbester9050 Ай бұрын

The driver is 98, but real thirsty!

@Sqrt.Infinity Ай бұрын

But how old are the watermelons?

@milanstevic8424 Ай бұрын

But how many watermelons were there?

@redplanetzeal1461 Ай бұрын

To be fair, the question does not mention that the dry weight remains the same during the journey, so we can come up with any numbers for the answer, as long as the water content is 98%.

@ThinkOpenlyAtGMail Ай бұрын

You have the calculation of "final dry weight" misrepresented at 6:34. It shows "d = 0.1(100)", when it should show "d = 0.01(100)". (FYI)

@ralanham76 Ай бұрын

For me the visual part makes sense if the dry weight was 2 yellow dots with 98 blue then " simplify" to 1 yellow and 49 blue.

@ambhaiji Ай бұрын

0:10 I think an attempt was made to do the 'in the beninging' meme and then decide halfway to follow a civilized scientific discourse.

@MachineCake Ай бұрын

I think one reason for the confusion by many people is because they (like I did initially) interpret the "water content" as a percentage of the VOLUME instead of the WEIGHT. I pictured watermelon-shaped containers 99% full of water changing to 98% full of water, which is a different problem. :P

@LLlAMnYP Ай бұрын

What changes if it's volume? Just like weight, the overall volume would reduce as well.

@lifeisajourney4340 Ай бұрын

@@LLlAMnYP Bro, What if it was 98% water, 1% Dry stuff, 1% Vacuum? Consider the watermelon is a closed system.

@LLlAMnYP Ай бұрын

@@lifeisajourney4340 > watermelon is a closed system Awww, hell no it ain't! XD

@lifeisajourney4340 Ай бұрын

@@LLlAMnYP What about the other question?

@RedFloyd469 Ай бұрын

@@LLlAMnYP if it's just a single percent drop in volume, there is no guarantee it would equate to 50kg, or 40kg or 37kg, or anything, because we don't know what the volume to weight ratio is. This was my problem too, and couldn't seem to solve the equation this way.

@KaryoSentiko 16 күн бұрын

I'm a maths teacher, and I think the problem here is in the application. There has been a movement ( a good one in theory ) to teach maths in context as much as possible, as this makes it more engaging, easier to understand and more valuable. Hence a question about watermelons instead of just algebraic questions. But if you're going to write a contextualised question, you are signalling to the reader/solver that it makes sense in the real world. So they will expect the answer to be somewhere within the realms of predictability. If one were to guess, no maths involved, how much the watermelons would reduce, one might expect an answer in the realm of a few kilos, so their expectation would confirm the mathematically wrong answer. The mathematically correct answer here is absurd in real world terms. So, don't bother contextualising the question in the real world if it doesn't actually make any sense in the real world. This goes for any question like, "Little Johnny is trying to find the ratio of white flowers to yellow flowers in the meadow by his house" or whatever ridiculous scenario. There has never been a little johnny who wanted to work that out. This is not a real world example. Has never happened. Will never happen. Try harder or don't bother!

@victorfinberg8595 23 сағат бұрын

if you're going to discuss these puzzles as more than "bar tricks", you really should eliminate errors like 1) MASS is not WEIGHT 2) % of total is given in terms of MASS or VOLUME

@verkuilb Ай бұрын

It becomes easier to visualize, if instead of saying “99%” and “98%”, you say “99/100ths” and “49/50ths”. Still challenging for many, but that difference in the denominator helps some people.

@jonathanodude6660 3 күн бұрын

silly point. 98% is a real percentage used all the time. converting to a fraction and simplifying it is taught in primary school. children learn to do this.

@ListentoGallegos Ай бұрын

I love questions like these because they expose many people to the realization that their intuition is misleading.

@tench745 17 күн бұрын

The thought that illustrated to me just how much weight it would lose is realizing that 50% water content would weigh only 2kg.

@NotKnafo 16 күн бұрын

i remember this one but with potato they lose half of their mass because the 1kg solid content does not change and in order to get 2% solid from 1% you need to halve the water content

@hdthor 17 күн бұрын

The better way to think about it to use units that are invariable rather than units that are variable. Water content is variable, so let’s rephrase it into ruffage content (non-water content aka dry weight). The ruffage content was 1kg at the beginning. At the end, the ruffage content can’t be 2kg. The 2% ruffage means the total weight is 50kg, so the ruffage stays constant at 1kg.

@FreyGrimrod Ай бұрын

A PhD doesn't mean you are smart it means you are determined and willing to be hazed with trauma.

@harisimer Ай бұрын

No, a PhD shows a special aptitude for scientific work and research. If you are smart that very well might make a difference

@Kupferhans Ай бұрын

@@harisimer I think both cases exist. It would be ideal if everyone had a special aptitude for scientific work. But many people just want to have the degree because it helps them with their carreer and so they torture themself through it.

@JaneAustenAteMyCat Ай бұрын

Oh there's an American politician with a PhD who used the slogan 'Jesus, Babies and Guns' - I forget her name - and who believes the earth is flat and that we live in a 'globe conspiracy'. That might just be a reflection on American universities, I don't know...

@furbyfubar 19 күн бұрын

It baffles how/why someone could think substituting watermelons with potatoes would make sense. What type of potato would have its water content be 99%? Google tells me that raw potatoes contain ~79% water, and cooking them only brings that number down. But because this riddle/paradox is mentioned so many times online, google suggest questions like "Are potatoes 99% water?" and then give the "suggested answer" from a page rephrasing this riddle.

@cookesam6 Ай бұрын

Man it makes you feel good when you get these right

@woodward4789 Ай бұрын

Imagine losing 50kg of water to summer heat. Those melons must be shrivelled messes

@melissascheid841 Ай бұрын

You forgot to ask the fundamental question, " What is the definition of water content / moisture content?" In soil mechanics, the definition of moisture content is the mass of the water divided by the mass off the solids. With this definition, you get very different results. This definition results in the mass of the solid to be 50.25 kg and the initial mass of the water to be 49.75 kg. The final mass of the water is 49.25 kg resulting in a final mass of the melon to be 99.50 kg.

@mab06 26 күн бұрын

Nonsense. You have inented an ambiguity that does not exist.

@michaelgleason4791 3 күн бұрын

Just because you can't say the ambiguity does not make it nonsense. That's a pretty narrow view of the world.

@jonathanodude6660 3 күн бұрын

@@michaelgleason4791 we arent talking soil mechanics nor did he say moisture content. clearly, using a water:not water ratio will give different answers to a water:total ratio.

@yurenchu Ай бұрын

From the thumbnail: 50 kg. Due to the drying out, [99 kg water + 1 kg non-water] changes into [49 kg water + 1 kg non-water] , so the water content changes from 99% to 98% . 10 minutes of explanation? Okay, let's watch.

@A-Negative Ай бұрын

I hated math, algebra, and calculus. Until you walked through this problem. Wow. I clearly had subpar teachers. Perhaps I would have stayed in the science field. Kudos.

@baze3541 Ай бұрын

I had the worst math teacher in high school and yet that did not hold me back from math or anything

@MarcoMagallanes-p2w Ай бұрын

@@baze3541Same my math teacher in highschool was so strict that everyday the test is different from what.we learned which yeh it's just so strict and evil She told us to advance in the book And she gave us a test that wasn't In the book and yeh I call her evil and strict

@jonahansen Ай бұрын

Yeah, well I loved science and math, but I often see arguments that make something so clear I realize my teachers were not all first class. The super-great teachers are few and far between, but could really improve the learning for students having a hard time. I suppose that is the mark of a good school, where the school recognizes and hires the best teachers.

@Doeniz1 Ай бұрын

I thought there was some trick involved and was pretty disappointed, when the solution turned out to be just the straight foreward approach.

@marcusscience23 Ай бұрын

One way to think of it is that the percentage of dry weight goes from 1% to 2%, so it doubles. Along with the fact that the amount of dry weight remains constant, in order for the percentage to double, the total weight must halve, so the final weight is half of 100 kg, 50 kg. 50 = 100/((1-98%)*(1-99%))

@Stooge2 Ай бұрын

That makes so much sense, thanks!

@jamesdlin7 24 күн бұрын

Yes, I think it's interesting that reformulating the question to be "the dry weight percentage increased from 1% to 2%" probably would produce much different results.

@g.h.190 Ай бұрын

So many comments suggesting question is badly worded. To me it sounds like they are trying to invent an excuse for their failed answer.

@MaulikParmar210 Ай бұрын

English across world is pronounced and written differently, people will get it wrong even if relative grammar is correct. Comprehensive skills do not work when question is deliberately worded to create confusion and change meaning which could be expressed with more words. Welcome to languages 101.

@driftwisp2797 8 күн бұрын

Question isn't "badly worded", but it is misleadingly worded. And intentionally so. Something is paradoxical if it leads to a counter-intuitive outcome, but in this case it isn't the outcome that's counter-intuitive but the situation itself. The wording leads you to believe that it went from "99 parts water" to "98 parts water". "Water content" can also refer to either mass or volume, which can add another layer of first glance processing to distract from the actual situation. If you give a more clear wording that lends itself to understanding the situation better, like "99% of the original 100kg weight is water" and "98% of the new weight is water" suddenly a lot more people will get it right on the first try.

@jonathanodude6660 3 күн бұрын

@@driftwisp2797 99% water content and then 100kg total mass is very unambiguous, obviously its 99% by mass, ie 99kg they never mentioned any volume, so how can you assume it? sounds like excuses to me. if you do not understand what 98% by mass means then maybe you would have trouble. saying "the water content is now 98%" is functionally identical to saying "98% of the new weight is water" because that is what water content means. it is not badly worded nor is it misleading. I am 52 seconds into the video and i have solved it.

@jameswalsh318 2 күн бұрын

The problem most definitely was ambiguously worded. The correct answer is that the final weight of the watermelon batch can not be determined. The problem said "... In the beginning, their water content was 99%. ...". But their water content was 99% of WHAT? Was it 99% of the total weight of the watermelons (which would make their water content 99 kg) or was it 99% of the weight of the watermelons original water content, which was not told to us? It should have said "In the beginning, their water content weight was 99% of the total weight of the watermelons".

@jonathanodude6660 Күн бұрын

@@jameswalsh318 the only explanation for your misunderstanding is that you simply don’t know what “water content” means. That’s not the fault of the question, nor does it make the question poorly worded. If I asked you a puzzle about harmonic oscillation and you thought I was talking about music, that would not mean that the question was poorly worded, because that is the correct name for the phenomenon. The water content of a material is the amount of the material that is water. A water content of 99% means that 99% of the material is water. The question immediately states the material weighs 100kg. The assumption therefore is that 99% corresponds to mass (% w/w), not volume, not density, not refractive index nor anything else. If you’ve ever seen milk say “99% fat free”, it’s not because they removed 99% of the fat present, it’s because 1% of the reduced fat milk is fat and 99% is everything else (water, protein, calcium, etc). That is poorly worded in my opinion. Saying the water content is 99% is correct and the mass immediately provides a disambiguation of the units used to calculate the 99%. If the water content becomes 98%, that means enough water has evaporated to change the total amount of everything and there is a new ratio of water to everything else. This is meaningless information unless we know that the mass of everything else is. Fortunately, there is context behind the question that lets us assume that the mass of everything else never changed. Hence 1kg is now 2%, therefore the total is 50kg.

@Keixxo Ай бұрын

When you first started explaining the answer, I was so irked, because I was sure that was wrong.

@whoknows8413 17 күн бұрын

This problem is solvable only if you assume that when you say something is 99% water, you mean 99% by weight. However, that is a false assumption. Most people, when they are told something is 99% water, they take that to mean that the volume of the said object is 99% water. Thus you have here two unknowns, you don't know how much the water weighs, and neither do you know the weight of the vegetable component of the watermelon. Therefore, this problem is unsolvable.

@richardlongman5602 Ай бұрын

But did your result answer the question asked? They asked the final weight, so the answer should be either 110 pounds or 490 newtons. kg is a unit of mass.

@Nethuja_GunawardaneSL Ай бұрын

Come on dude, don't make it even more complicated

@davidellis1079 Ай бұрын

Leaving aside the fact that the pound is a mass unit, you are oversimplifying matters. Weight including or excluding the buoyancy force due to displaced air? Which definition of weight are you using? The latter could be significant in an accelerated environment such as the surface of the rotating earth. And that's only for starters... 😉😂

@NichaelCramer 24 күн бұрын

I’m glad you included the final, more “visual” solution. It’ll help, for example, in “dinner-table discussions” where I might want to explain this interesting example to folks who aren’t interested in (or who might not follow) “all that algebra stuff”.

@simonliljeqvist Ай бұрын

Interesting to me is that removing more than half of the water (50/99) only decreases the water content by 1% units Edit: I meant concentration or ratio instead of content

@elSethro Ай бұрын

Looking at it the other way: "NOT water" has DOUBLED from 1% to 2%. This is a huge change. Since "NOT water" it is a constant (1kg both before and after), then water weight must have halved to produce that change.

@themyief2406 Ай бұрын

you are wrong here, the 99% was in terms of the starting weight but the 98% was in terms of the final weight.

@leif1075 Ай бұрын

@@themyief2406yeaisnt the accurate way to say it you reduced the water content by 1 percent. Yea that's right. Because it dropped from 99.percent to 98 oercent water..so it's loterally correct to say the water content dropped by 1 percent..not sure where he got 50/99 from.

@frankieking1941 Ай бұрын

Thank you for your coment, now I understand……..I think😅

@themyief2406 Ай бұрын

@@leif1075 Ok, I had a hard time understanding your comment as it has improper grammer, but I think what you meant by your comment was "It is alright to say that the water content dropped from 99% to 98%". But that would be incomplete, as it should be, "the water content dropped from 99% of starting weight to 98% of final weight". Edit: Also it is incorrect to say that the water content dropped by 1% as the basis of measurement (i-e starting weight and final weight) are not same.

@IMarvinTPA Ай бұрын

I worked it out by trying to get the equation to calculate the water weight, so I ended up with (w - d)/w = 99%. Substituted in the dry weight at 1 and solved for 98%. When I got 50, I figured I was wrong and to just watch the video.

@kurzackd Ай бұрын

3:32 -- mate, *you're **_VERY_** WRONG ...* We are told in the riddle that the ratio of *volume of **_MATTER_* is 99 water to 1 fruit.... *NOT* that the ratio *OF WEIGHT* of water to fruit is 99 to 1... -_- Substances have different densities, you know ?? -_- *REAL ANSWER:* The watermelon has lost 1/99 of its weight during the trip. 1/99 of 100 kg is 1.01 kg. Therefore THE FINAL WEIGHT of the watermelons is ... 100 kg - 1.01 kg = 98.9898(repeat) kg... -_- *PERIOD.* .

@ExtraTrstl 19 күн бұрын

But if we don’t assume these ratios are weight, how are you getting an alternate answer? E.g.,, couldn’t the melon portion weigh 40kg, and the water portion weigh 60kg? If that’s the case wouldn’t your alternate answer be wrong?

@driftwisp2797 8 күн бұрын

@@ExtraTrstl I got the same answer they did from the same assumption. My first thought was "That's volume, not mass, right?" and then I decided to play along with "Well, if we assume that the mass is that proportion too..", but since I had already imagined the scenario by volume I found the mass in that scenario instead of the one they were asking for. That's the thing about this paradox, it's not a situation leading to an unexpected result so much as a trick designed to make you misunderstand the situation. And that's also why people complain about it not being a "real" paradox. Any situation can be paradoxical at first glance if you word it poorly enough, and this feels like a more elegant version of that fact, rather than an inherently paradoxical situation.

@jonathanodude6660 3 күн бұрын

nope youd get the same answer. it was 1 fruit to 99 water before (total 100) and then it was 2 fruit to 98 water after (total still 100). 2:98 can simplify to 1:49 (divide numerator and denominator by 2) and you get the solution.

@driftwisp2797 Күн бұрын

@@jonathanodude6660 Imagine you have a spherical watermelon shell that weighs 1 kg. Now imagine it's 99% full of water, and the water weighs 99 kg. Some of that water evaporates, and now it's 98% full of water. What does it weigh? It weighs 98.98kg. That's the most intuitive scenario when you're viewing the water content as a percentage of volume, because any water that evaporates off will be replaced by air. That is also not the situation the problem is actually talking about, which leads to people feeling mislead.

@jonathanodude6660 Күн бұрын

@@driftwisp2797 ok but now we are talking about volume measurements which were not given in the question.

@Kitasia Ай бұрын

The question is confusing because you don't know what the 98% is referring to. 98% of the original whole or 98% based on the end ratio.

@wiggles7976 Ай бұрын

It means "98% water by mass." The total mass is M, and the mass of the water is W, and the mass of the watermelon rind is R. M = W + R, and 0.99M = W, and 0.01M = R.

@Kitasia Ай бұрын

@@wiggles7976 That formula works but, the interpretation opens a bit after dropping to 98% W = 0.99, R = 0.01 thus M = 1 Okay W/M = 0.99 (99%) Does the formula become W/M(initial) = 0.98 (98%) thus W = 0.98 R = 0.01 M(new) = 0.99 or W/M(new) = 0.98 (98%) thus W = 0.49 R = 0.01 M(new) = 0.5 It depends entirely on the frame of reference.

@jonathanodude6660 3 күн бұрын

@@Kitasia if the water content changes, the ratio has changed. the water content of an object in the presence has no dependence on the ratio of that object in the past. W is W(new). W(new)/M(initial) bears no connection to reality. M is always solids + water. changing the water content changes M.

@litcrit1624 Ай бұрын

I always did this one in my head. Originally the dry melon 1 kg was 1% of the whole; now that same 1 kg is 2% of the whole. So how much do you have to multiply that 2% to get up to 100%? 50. I have a feeling it would've been harder if the number is weren't so easy to keep in your head.

@RajveerSingh-vf7pr Ай бұрын

No wonder why so many PHDs could not solve it, you guys really know how to over-do a problem. 1kg had to contribute for 1% in the beggining, now, 1 kg have to contribute for 2%, just double, which means half of it is gone... Edit: I am just a nobody, tourist guide in India, I don't mean to insult anyone.

@GavrielFleischer 9 күн бұрын

I guess the mathematicians at the BBQ have not only drink watermelon juice... probably some alcohol as well.

@geoninja8971 Ай бұрын

Very cool. I started writing some equations, and soon worked out to convert everything to % of solids, then it all fell into place....

@dunsparce4prez560 Ай бұрын

But… but. You’re saying a collection of 100 kgs of watermelon, in real 3D space, in some guys back yard or on a train or whatever, loses 1% water content and therefore loses 50% of its weight? I get the math but i don’t get the correlation. If i have a bucket of water and 1% of it evaporates it does not get 50% lighter. How is this not just an unexpected result?

@andrasferencz7948 Ай бұрын

I have solved it quickly with a method very similar to your latest solution. If 1kg dry part was 1% but becomes 2%, then 100% will be 50kg, which results 49kg of water. Q.e.d Talk to any finance guy (I'm an engineer, not a finance guy) about bond coupons and bond prices on secondary markets. Assume the prevailing interest rate is 1%. Someone issues a long term bond, with a $100 face value, and a 1% yield, which means that every year you will get a $1 coupon payment. Next year the inflation goes up, and the market will demand a 2% yield. What will be the price of the bond? Well, the bond will be traded for $50, because this way the $1 payment (the promised coupon) will mean a 2% yield, as demanded by the market. Obviously this will is a simplification (time to maturity, how sound is the issuer, and so on), but it is exactly the same idea.

@olmostgudinaf8100 Ай бұрын

That is not a paradox. It's just a puzzle. A paradox is a puzzle that has two mutually exclusive solutions.

@priyankkhemka1188 3 күн бұрын

Why does dry waste has to remain unchanged? If the overall weight goes down, won't the dry weight go down as well?

@PKua007 Ай бұрын

I didn’t expect that low mass at the end, but I knew you couldn’t just subtract 1kg, so I decided to write it down and solve it carefully and got the correct result

@jeopardy60611 10 күн бұрын

I thought the answer is 98,.99 kg. If the watermelon consists of 99% water, you can't say that it goes all the way down to 50 kg when you only lose 1% of the water weight. 1% is nowhere near half or 50%, so how can you say that the whole thing goes down by 50%?

@outdxal5352 Ай бұрын

{Time: 6:55} Why is d= 0.1(100)=1

@g.mitchell7110 Ай бұрын

I knew the answer right away, and not because I saw the same problem on Vsauce2 (The Potato Paradox). That video is about potatoes and this one is about watermelons. These are different types of food altogether.

@tolkienfan1972 Ай бұрын

Lol

@emurphy42 Ай бұрын

Sorry, I only know how to solve this for oranges.

@dirkbester9050 Ай бұрын

True, you can just plant the potatoes and hope for better luck next year. The watermelon in the picture are seedless, so no such luck.

@JLvatron Ай бұрын

I got this right, but at 3:58 it is an assumption that the solid mass remained as this was never made clear in the question.

@camelopardalis84 Ай бұрын

@@JLvatron You are right. It is only implied.

@camelopardalis84 Ай бұрын

You are right. It was only implued, which is indeed not clear enough.

@bjorneriksson2404 Ай бұрын

Well, the "dry mass" can't exactly evaporate, so that mass remaining the same is an obvious deduction to make. Not everything should have to be "proven" in problems like this, because then you can start to demand proof of the fact that 50 is indeed half of 100 instead of just assuming that it is.

@TheEulerID Ай бұрын

Correct, and I have made the same observation, and it seems that, in addition to water, melons contain over 100 different volatile compounds.

@ModelLights Ай бұрын

@@bjorneriksson2404 ' "dry mass" can't exactly evaporate' Dry mass can't evaporate, and taking out 1% from the water weight doesn't make water magically drop to 50 kg from 99 kg. You guys realize at the 4:30 mark where the math is taking the ALREADY REDUCED TOTAL WEIGHT of 99 kg and multiplying it by '98%' which is NOT THE WATER REDUCTION FACTOR to get the 'paradox' is bad math, not a paradox, right? OF COURSE it reduced it too far, that 98% is self references 100%, not 'only the water weight reduction starting at 99%'. This is brain rot, I highly suspect the whole 'bunch of PhD's all arrived at this same answer after being told it was wrong' is completely made up garbage. If it was 100% water weight, and it reduced a percentage to 99% water weight, it would be 99 kg, it would NOT magically jump down to 50 kg from a 1% reduction. This is ONLY THROWN OFF A TINY BIT by 1 kg of the 100 being solid and not reducing by its 1% as well.

@andreketaren Ай бұрын

I checked the truck's cctv and saw some burglars stole half of the watermelons

@toshogme 6 сағат бұрын

the only way for this to work is if the melons shrunk in size or someone ate half the melons ....

@jamiewoodhouse6238 Ай бұрын

Wrong. From the initial statement, we do not know that the 1% non-water part weights 1kg. What indicates if the 1% non-water part is 1% by weight, or 1% by volume. I am assuming the latter, and so the answer is ‘indeterminable’? Thoughts?

@AUSinCH 14 күн бұрын

Hey Presh, there's a typo in one of your expressions. You mention that the dry weight (d) is 1% of the total weight, and you express this as: d=0.1(100)=1. The 0.1 should be 0.01, of course. Just mentioning this as some viewers might get confused by what they see on the screen.

@andrzejsamorzewski146 Ай бұрын

Real watermelon water content is about 92%. How some one can get PhD in science but fail on elementary school math, this is the real paradox.

@jespado Ай бұрын

I solved it in my head in 30 seconds. I must be a genius!

@Goldenblade14 Ай бұрын

Lately, the "unsolvable" math questions have been more "poorly written" questions.

@DaSquyd Ай бұрын

I wouldn't consider this one to be "poorly written" though.

@johncheshirsky8822 Ай бұрын

@@DaSquyd exactly. Nor does it pose itself to be "unsolvable", more like "unintuitive". "Tricky" at worst. But that's the whole point.

@GooogleGoglee Ай бұрын

Absolutely 💯 agree.

@robertveith6383 Ай бұрын

@@DaSquyd -- You missed understanding how it is poorly written.

@DaSquyd Ай бұрын

@@robertveith6383 I mean, I must have since I solved the puzzle.

@portobellomushroom5764 Ай бұрын

Veridical paradoxes are the lamest form of paradoxes, and as someone whose intuition steered me directly into the correct answer I'm calling this not even a veridical paradox.

@marvhollingworth663 Ай бұрын

You overcomplicate the answer. I just did the dry weight is 1kg, which has to be 2%. So 1kg*50=50kg.

$@fractalzoomgoggles$

@fractalzoomgoggles Ай бұрын

You overcomplicate the answer. I used a scale

@peterrose5373 15 күн бұрын

Fewer people would get it wrong if the scenario weren't so implausible. losing 50 kg of water during shipping doesn't seem reasonable. Losing 1 kg or so does.

@jameswalsh318 2 күн бұрын

This was an unfair question because it was not stated clearly. The correct answer is that the final weight of the watermelon batch can not be determined. The problem said "... In the beginning, their water content was 99%. ...". But their water content was 99% of WHAT? Was it 99% of the total weight of the watermelons (which would make their water content 99 kg) or was it 99% of the weight of the watermelons original water content? If we do not know the percentage of original water content then we can not answer the question. (This could be, let's say, 50%, 60%, 80% or whatever it is. But that percentage of total weight, or the weight itself in kg, was not told to us.)

@anilchandrapoudel3257 25 күн бұрын

Initially, Total mass=100kg watery% =99% Non watery mass =1%of 100kg =1kg Eventually Also non watery mass=1kg Total part=x kg(less than 100 kg obviously because of drying up of water) Watery%=98% Non watery mass=2%of total Total mass=non watery mass /2% X= 1/2%=50kg

@kamen42 17 күн бұрын

I am disappointed this needed a 10 minute video. This thing is so simple I was sure there is a second riddle after it.

@delanomighty8113 Ай бұрын

This is one of the first things we do as chemical engineers. The key is to do the calculations on the amount that does not change - i.e., the 'dry' mass.

@TonboIV Ай бұрын

So I was able to find the correct answer (after trying the intuitive answer and then sanity checking it and realizing it didn't work), but I think the wording is ambiguous. "dropped to 98%" implies that we're talking about a percentage of the same thing, because of the word "dropped". Assuming this is percentage by mass, "dropped to 98%" implies a decrease from 99% of 100kg to 98% of 100kg. Something like "By the time I reached the destination, the water content _was_ 98%" would be better because it implies a completely new percentage. In general, I think we all tend to be a bit inconsistent in how we talk about changes in percentages. If I say "It started to 60% and then decreased by 50%", is the new percentage 10% or 30%? I think either could be argued.

@mstreich Ай бұрын

I’m not convinced that 99% of the content is water leads to 99% of the weight is water. Think of a heavy bucket. It’s possible for the bucket that takes up a fraction of the content to weigh almost any % of the total weight. 3:37

@skachor Ай бұрын

If its 99% water, its 1 kg of watermelon and at 98% ill just round it back to 1kg of watermelon.

@MrSaemichlaus 12 күн бұрын

I deeply distrust percentages because they have betrayed my intuition a good number of times. So I went through it very rigorously and skeptically and arrived at the correct answer from the beginning. Maybe getting the correct answer or rather, not getting the incorrect answer without noticing, involves a good portion of knowing your limits. I did it in only two simple steps: 1. the initial "dry" percentage is 1% of 100kg so that's 1kg. 2. the end "dry" percentage is 2%, so the total weight is 1kg / 2% = 50kg

@Able89535 Ай бұрын

The terms “Absurd” or “counter-intuitive” are subjective, highly depends on your knowledge and your mindset (how you view the problem at first sight). Hence the term “Veridical paradox” is also subjective and some can think that it is, while others may think it’s not.

@IvanToshkov Ай бұрын

This is one of the reasons I'm always suspicious around percentages. They can be quite counter-intuitive. And the press *loves* to use them all the time.

@BryanLu0 Ай бұрын

A veridical paradox isn't really a true paradox. Yeah, it might have paradox in the name, but that doesn't automatically make it a paradox.

@nicholasharvey1232 Ай бұрын

I think of it this way: we know there is 1kg of dry weight before the drying-- making up 1% of the total weight-- and still 1kg of dry weight after, but now it's 2% of the total weight. And what is 1kg 2% of? 2% is 1/50, so it must be 50kg total weight!

@connectedtonature8299 Ай бұрын

Water Content Dropped to: 49Kg Solid Content remain: 1Kg Total Weight of the melons: 50Kg

@wryskee1 Ай бұрын

just because 99% of the object is water doesn’t make 99% of the weight water because water has a different density than the other things in watermelons

@Luigi_Luigi2401 Ай бұрын

I dont think this question is written clearly because i thought that the water would decrease and more of the watermelon would be dry I didn't interpret it that the dry part would stay unchanged

@jasonsmall5602 Ай бұрын

None of it is dry

@ghostAFsky Ай бұрын

How would dried water turn into more watermelon...? That doesn't make any sense.

@floppy8568 Ай бұрын

Simple: 1% not-water becomes 2% not-water, so the amount of not-water doubles; 99/100=99%; 49/50=98%. So the answer is 50kg!

@rennleitung_7 Ай бұрын

The percentage of water of a watermelon by weight is give or take 90% . So in real life the 99% only make sense if you treat the watermelon like a bottle or a sponge and the percentage is the content of the maximum water, the melons can hold, which by the way is the same with air humidity. 99% air humidity doesn't mean, that the air is made of 99% water.

@joziahelliott1976 12 күн бұрын

you could also just assume it gained more watermelon weight to make the water value stay the same but go down to 98% the wording is off and doesn't make the most sense

@Misteribel Ай бұрын

98% water + 1% ice + 1% other = 100%. Total weight 100kg. In a closed system, mass doesn't change. However, if you travel, weight will change depending on the location on the globe. Not enough info to answer the question.

@steveknight878 2 күн бұрын

I worked it out by saying 1kg of dry weight of the original represents 1% of the total weight. After the journey, that 1kg represents 2% of the total weight (100 - 98). So 1kg = 2/100 x the final weight w. 1kg = 1/50w means total weight is 50 kg

@jmadratz 13 күн бұрын

They were not mathematician or physics or engineering PhDs. This is a high school problem.

@nickhill9445 Ай бұрын

I calculated: If 99% then 1Kg dry, 99Kg wet. If it were 100Kg, and was 98% water, then 2Kg dry, 98Kg wet. Since we still have 1Kg dry, then it must be half of 100Kg.

@t-rex4211 2 күн бұрын

Water weighs 1kg per litre. If you lose 50kg you lose 50 litres. Average weight of a water melon is 14kg with 92% water. 7 watermelons to lose 50kg/50 litres between them would mean they’ve lost just over half their weight. Im calling bs 😉

@jakubkrcma 6 күн бұрын

Before watching the video, I say 50 kg. 99% water content means 1% non-water content. That is 1 kg out of 100 kg. Since 98% water content means 2% non-water content. 1 kg is 2% of the final weight. Thus, the final weight is 50 kg.

@sonicwaveinfinitymiddwelle8555 Ай бұрын

He's explaining this question like he answered this question right on the first try.. I mean I got it right but is this a bit exaggerating?

@BradHouser 19 күн бұрын

It is also interesting to note that if you want to dilute a liquid that is already 98% water, you would have to more than double (increase by 50/49) the water content to reach 99%.

@davidthibodeau753 Ай бұрын

I bet farmers are more likely to get this right than PhD scientists. This type of calculation is common when working out the final weight of corn as dry grain.

@reidflemingworldstoughestm1394 24 күн бұрын

Trick question. Nobody weighs watermelons in kg. They are a north american crop plant.

@Chilloutdude93 Күн бұрын

I guessed it right, if water evaporated,the mass would remain same,that means initially 1% is 1kg At last 2% was 1kg , therefore 2%--- 1kg 100%--- 50kg.