A population has a mean of 60 and a standard deviation of 18. A sample of 81 observations will be taken. The probability that the sample mean will be larger than 64 is
A) 0.5228.
B) 0.9772.
C) 0.4772.
D) 0.0228.

Question

Quizplus · Accepted Answer

The standard error of the mean is 18/sqrt(81) = 2. The z-score for a sample mean of 64 is (64-60)/2 = 2. The probability of a z-score greater than 2 is 0.0228.

A Population Has a Mean of 60 and a Standard