The Office of Student Services at a large western state univ

The Office of Student Services at a large western state university maintains information on the study habits of its full-time students. Their studies indicate that the mean amount of time undergraduate students study per week is 20 hours. The hours studied follows the normal distribution with a standard deviation of six hours. Suppose we select a random sample of 144 current students. What is the probability that the mean of this sample is between 19 hours and 20 hours?

A. 2.00

B. 0.4772

C. -2.00

D. Cannot be calculated based on the given information

Solution

cannot be calculated with given data

because we either need mean or standard deviation to z-value

and probability = 1-z-value