CRA CDs Inc. wants the mean lengths of the " cuts " on a CD to be 135 seconds (2 minutes and 15 seconds). This will allow the disk jockeys to have plenty of time for commercials within each 10-minute segment. Assume the distribution of the length of the cuts follows the normal distribution with a population standard deviation of 8 seconds. Suppose we select a sample of 16 cuts from various CDs sold by CRA CDs Inc.
a. What can we say about the shape of the distribution of the sample mean ?
b. What is the standard error of the mean ?
c. What percent of the sample means will be greater than 140 seconds ?
d. What percent of the sample means will be greater than 128 seconds ?
e. What percent of the sample means will be greater than 128 but less than 140 seconds ?