CRA CDs Inc. wants the mean lengths of the “cuts” on a CD to be 140 seconds (2 minutes and 20 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 23 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? (Round your answer to 2 decimal places.)
(c) What percent of the sample means will be greater than 145 seconds? (Round your answer to 2 decimal places.)
(e) What percent of the sample means will be greater than 133 but less than 145 seconds? (Round your answer to 2 decimal places.)
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