Homework Help: statistics

Posted by Amy on Friday, March 9, 2012 at 3:23pm.

In a population of exam scores,a score of X= 48 corresponds to z= 1 and a score of X= 36 corresponds to z= -.50. Find the mean and standard deviation for the population?

statistics - Reiny, Friday, March 9, 2012 at 4:03pm
z-score = (x-mean)/sd

1 = (48-m)/s
s = 48-m
s+m = 48 , #1

-1/2 = (36-m)/s
(-1/2)s = 36-m
-s = 72 - 2m
2m - s = 72 , #2

add #1 and #2
3m = 120
m = 40

then s+40 = 48
s = 8

mean = 40 , SD = 8

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