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?

Astudent is determining the influence of different types of food on the growth rate of spiders. she feeds one group of spiders two caterpillars twice a week. the other group received similarly-sized beetles twice a week. she records the amount of time required for individuals to reach sexual maturity. her hypothesis is that the spiders feeding on caterpillars will have a faster growth rate because caterpillars have a higher protein content compared to beetles. in this experiment, what is the dependent variable? spiders assigned to different feeding groups. time required to reach sexual maturity number of prey items fed twice a week. growth rates of each group.