to the following question based on the following scenario 21

to the following question based on the following scenario: 21 students took an introduction to psychology test. The class average was an 82 and the standard deviation was 12 assume that the results are normally distributed
a. the students scoring in the top 2% on the test had test grades above what
b. the students scoring in the bottom 2% had test grades below what
c. approximately how many students received a B on the test

Solution

let X~N(82,12²)

a. the students scoring in the top 2% on the test had test grades above what

we need to find x such that

P(X>x)=0.02

x= 106.645

b. the students scoring in the bottom 2% had test grades below what

here also we need to find x such that

P(X<x)=0.02

x= 57.3550