Statistics Question

Question

For a normal population with μ = 70 and σ = 12, find the following.

(a) What is the probability of obtaining a sample mean greater than 73 for a sample of n = 36 scores?

(b) What is the probability of obtaining a sample mean greater than 73 for a sample of n = 9 scores?

Answer 1

a) P(M > 73) = P(Z > (73 - 70)/(12/sqrt(36))) = P(Z > 1.5)

b) P(M > 73) = P(Z > (73 - 70)/(12/sqrt(9))) = P(Z > 0.75)