00:01
So for the standard scores, we want to see which students did better as a freshman or senior, and we're going to do that by standardizing these with the z -score.
00:10
Z is going to be our data point minus the mean over our standard deviation.
00:14
So for the freshman scores, i'm going to go 57 minus 53 over 7, 51 minus 53 over 7, 45 minus 53 over 7.
00:27
For the senior scores, i'll go 97 minus 92 over 4, 94 minus 92 over 4, and 82 minus 92 over 4.
00:39
So i'm going to go ahead and do some of these.
00:41
That's going to be 5 over 4, which is 1 .25.
00:45
This is going to be 2 over 4, which is 1 half or 0 .5.
00:49
This is going to be negative 10 over 4, which will be negative 2 .25.
00:54
Now these i can't do in my head, so this is going to be 4 sevenths, which is going to be 0 .57.
01:03
Here we're going to have negative 2 sevenths, which is going to be negative 0 .29, and then here we're going to have negative 8 sevenths, which is going to be negative 8 sevenths is going to equal to negative 1 .14.
01:24
So the one with the higher z score is the one that they did better.
01:28
So for a, they did better as a senior.
01:32
For b, they did better as a senior.
01:35
For c, they did better as a freshman.
01:37
So now we want to know the probability that the following ranges as a score as a freshman, and we want these particular values.
01:48
Let me get my pen here.
01:50
We're doing freshmen, so we need less than 52 between 40 and 60, and then more than 62.
01:59
So we need to find the z scores for 52, 60, and 64, 52, 40, 60, and 62.
02:08
So we're going to do it the same way we did here.
02:10
52 minus 53, that's going to be negative 1 divided by 7...