15. Wildlife: Wolves A random sample of 18 adult male wolves from the Canadian Northwest Territories gave an average weight x1 5 98 pounds, with estimated sample standard deviation s1 5 6.5 pounds. Another sample of 24 adult male wolves from Alaska gave an average weight x2 5 90 pounds, with estimated sample standard deviation s2 5 7.3 pounds (Source:

The Wolf by L. D. Mech, University of Minnesota Press).

(a) Let m1 represent the population mean weight of adult male wolves from the Northwest Territories, and let m2 represent the population mean weight of adult male wolves from Alaska. Find a 75% confidence interval for m1  m2.

(b) 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 75% level of confidence, does it appear that the average weight of adult male wolves from the Northwest Territories is greater than that of the Alaska wolves?