Text tasks scare many schoolchildren and applicants, especially if they are tasks for mixtures and alloys. But now in 5 minutes we will deal with them!
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1 task - 0:12
2 task - 1:09
3 task - 2:22
In the next week we will manage with text tasks. There has already been a video on the topic of teamwork, but this time we will take mixtures and alloys. The main thing that is required of you is an understanding of what percentage is (simply the hundredth part of a number). Text problems on mixtures and alloys are a stumbling block for those who study mathematics in the 6th grade, and I hope this video will at least slightly improve the understanding of the material. The Unified State Exam objectives in the mathematics of the profile level (prototypes No. 11) on this topic are not difficult: the most difficult is at the end of this video. But, if you are good at dealing with percentages, then the “economic” tasks of the second part of the state exam will be on the shoulder. If you catch a buzz from mathematics - subscribe to the channel!
Terms of tasks.
#one. Grapes contain 90% moisture, and raisins - 5%. How many kilograms of grapes are required to produce 20 kilograms of raisins?
2. There are two rafting. The first contains 31% copper, the second - 25% copper. From these two alloys received the third. What percentage is the copper concentration in it, if the masses of the first and second alloys are 120 kg and 80 kg, respectively?
3. By mixing 30% and 60% acid solutions and adding 10 kg of pure water, we obtained a 36% acid solution. If instead of 10 kg of water, 10 kg of a 50% solution of the same acid were added, then a 41% solution of the acid would be obtained. How many kilograms of a 30 percent solution was used to make the mixture?
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Arithmetic # Tasks # Mathematics