The Normal Distribution with a calculator

Рет қаралды 51,676

5 жыл бұрын

A Level Maths revision tutorial video.
For the full list of videos and more revision resources visit www.mathsgenie.co.uk.

Пікірлер: 5

@lalayatem3758 3 жыл бұрын

this is really helpful thank you! God Bless

@L2K4S 5 жыл бұрын

16:00 I used 0.1 area and got -12.48 but converted it to 12.48 because logically standard deviation cannot be -ve, is this acceptable?

@possiblyunmatched1323 3 жыл бұрын

same here

@BrendanBourne 5 жыл бұрын

At 15:00 why did you use the probability of x less than 92 rather than x greater than 92 to get the second z value

@hamidas7890 3 жыл бұрын

We're told that P (X > 92 ) = 0.25 so we can infer that P (X < 92) = 0.75 this is an area of 75% so obvs passes the mean which we know is at 50% (i.e. in the centre of the bell curve). We then put the area as 0.75 into the inverse normal function to get a positive z value of 0.674 (indicating that the score is above the mean). If you use P (X > 92) we then have to put 0.25 as the area in the inverse normal function and we get - 0. 674 as the z value. The z value cannot be negative in this case as the score is above the mean. Sorry if this made no sense.