Wildlife: Wolves In the book The Wolf in the Southwest: The Making of an Endangered Species

(University of Arizona Press), the following weights of adult gray wolves from two regions in Old Mexico are listed.

Chihuahua region: x1 variable in pounds 86 75 91 70 79 80 68 71 74 64 Durango region: x2 variable in pounds 68 72 79 68 77 89 62 55 68 68 59 63 66 58 54 71 59 67

(a) Use a calculator with mean and standard deviation keys to verify that x1 5 75.80 pounds, s1 5 8.32 pounds, x2 5 66.83 pounds, and s2 5 8.87 pounds.

(b) Check Requirements Assuming that the original distribution of the weights of wolves are moundshaped and symmetric, what distribution can be used to approximate the x1 2x2 distribution?
Explain.

(c) Let m1 be the mean weight of the population of all gray wolves in the Chihuahua region. Let m2 be the mean weight of the population of all gray wolves in the Durango region. Find an 85% confidence interval for m1 2m2.

(d) Interpretation Examine the confidence interval and explain what it means in the context of this problem. Does the interval consist of numbers that are all positive? all negative? of different signs?
At the 85% level of confidence, what can you say about the comparison of the average weight of gray wolves in the Chihuahua region with the average weight of gray wolves in the Durango region?AppendixLO1