Refer to Exercise 59.

a. Construct and interpret a 95% confidence interval for the difference between the true means. If you already defined parameters and checked conditions in Exercise 59, you don’t need to do them again here.

b. Explain how the confidence interval provides more information than the test in Exercise 59.

Exercise 59.

Do birds learn to time their breeding? Blue titmice eat caterpillars. The birds would like lots of caterpillars around when they have young to feed, but they must breed much earlier. Do the birds learn from one year’s experience when to time their breeding next year? Researchers randomly assigned 7 pairs of birds to have the natural caterpillar supply supplemented while feeding their young and another 6 pairs to serve as a control group relying on natural food supply. The next year, they measured how many days after the caterpillar peak the birds produced their nestlings. The investigators expected the control group to adjust their breeding date the following year, whereas the well-fed supplemented group had no reason to change. Here are the data (days after caterpillar peak):

Control 4.6 2.3 7.7 6.0 4.6 -1.2 Supplemented 15.5 11.3 5.4 16.5 11.3 11.4 7.7