Cra cds inc. wants the mean lengths of the "cuts" on a cd to be 128 seconds (2 minutes and 8 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 6 seconds. suppose we select a sample of 21 cuts from various cds sold by cra cds inc. what can we say about the shape of the distribution of the sample mean?