00:02
Listed below our body mass indices of the same students included in table 9, 1 on page 489, the bmi of each student was measured in september and april of the freshman year.
00:15
Use a 0 .05 significance level to test the claim about the mean change in bmi for all students is equal to zero.
00:23
Does bmi appear to change during freshman year? well, given the paired data, we can find their differences.
00:30
The difference between 20 .15 and 20 .68 is negative.
00:37
0 .53 between 19 .24 and 19 .48 is negative 0 .24.
00:45
Between 20 .77 and 19 .59 is 1 .18 .18 is 1 .18.
00:50
Between 23 .85 and 24 .57 is negative 0 .72.
00:54
Between 21 .32 and 20 .96 is 0 .36.
00:59
Now the mean is the sum of all the values divided by the sample size.
01:03
So the mean of the differences would be found by taking negative 0 .53 plus, well, we can just then minus 0 .24 plus 1 .18, minus 0 .72 plus 0 .36.
01:26
And there are 5, which is 0 .01.
01:32
The standard deviation is the square root of some of the squares, the differences over and minus 1...