CRA CDs Inc. wants the mean lengths of the "cuts" on a CD to be 125 seconds (2 minutes and 5 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 13 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 130 seconds? (Round the final answer to 2 decimal places.)

Sample means %

d. What percentage of the sample means will be greater than 121 seconds? (Round the final answer to 2 decimal places.)

Sample means %

e. What percentage of the sample means will be greater than 121 but less than 130 seconds? (Round the final answer to 2 decimal places.)

Sample means %

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