Question

What is the probability of obtaining a sample mean greater than M=70 for a random sample of n= 16 scores selected from a normal population with a mean of μ=60 and a standard deviation of σ=20?

Answer 1

Solution :

Given ,

mean = = 60

standard deviation = = 20

n = 16

= 60

= / n = 20/ 16 = 5

P( >70 ) = 1 - P( < 70)

= 1 - P[( - ) / < (70 -60) / 5]

= 1 - P(z <2 )

Using z table

= 1 - 0.9772

= 0.0228

probability= 0.0228