Question

A sample of 81 students has a mean GPA of 3.25. The sample is normally distributed, and the sample standard error is found to be 1.0 grade points. Find the probability of a randomly selected student having a GPA of 3.0 or greater. (express your answer with 4 decimal places)

Answer 1

Solution :

Given that,

n = 81

= 3.25

= 1.0

P( > 3.0 ) = 1 - P( < 3.0 )

= 1 - P[( - ) / < (3.0 - 3.25) / 1.0]

= 1 - P(z < - 0.25)

Using z table,    

= 1 - 0.4013

= 0.5987