Homework Help: math

Posted by kevin on Sunday, March 28, 2010 at 7:51pm.

The mean score on a Math exam was 50% and the standard deviation was 10%. Assume the results were normally distributed.
(a) What percent of students earned a score between 50% and 70%?

(b) If 60 students took the exam, how many got a score between 50% and 70%?

math - PsyDAG, Monday, March 29, 2010 at 12:21pm
Z = (x - μ)/SD

Z = (x -50)/10

a) Get the respective Z scores. Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion between the two Z scores.

b) Multiply the proportion above by 60.

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