Question

A sample of size 82 will be drawn from a population with mean 24 and standard deviation 9. Would it be unusual if the sample mean was greater than 27? Why or Why not?

Answer 1

Solution :

Given that ,

mean = = 24

standard deviation = = 9

n = 82

= 24 and

= / n = 9 / 82

P( > 27) = 1 - P( < 27)

= 1 - P(( - ) / < (27 - 24) / 9 / 82 )

= 1 - P(z < 3.02)

= 1 - 0.9987

= 0.0013

Probability = 0.0013

Probability < 0.05

This is the unusual .