Question

CRA CDs Inc. wants the mean lengths of the “cuts” on a CD to be 148 seconds (2 minutes and 28 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 a normal distribution with a standard deviation of eight seconds. Suppose that we select a sample of 26 cuts from various CDs sold by CRA CDs Inc. Use Appendix B.1 for the z-values.

a. What can we say about the shape of the distribution of the sample mean?

Sample mean             (Click to select)  Normal  Uniform  Binomial

b. What is the standard error of the mean? (Round the final answer to 2 decimal places.)

Standard error of the mean             seconds.

c. What percentage of the sample means will be greater than 152 seconds? (Round the final answer to 2 decimal places.)

Sample means             %

d. What percentage of the sample means will be greater than 144 seconds? (Round the final answer to 2 decimal places.)

Sample means             %

e. What percentage of the sample means will be greater than 144 but less than 152 seconds? (Round the final answer to 2 decimal places.)

Sample means             %

Answer 1