Shoveling Heart Rates Because cardiac deaths appear to increase after heavy snowfalls, an experiment was designed to compare cardiac demands of snow shoveling to those of using an electric snow thrower. Ten subjects cleared tracts of snow using both methods, and their maximum heart rates (beats per minute) were recorded during both activities. The following results were obtained (based on data from “Cardiac Demands of Heavy Snow Shoveling,” by Franklin et al., Journal of the American Medical Association, Vol. 273, No. 11):

Manual Snow Shoveling Maximum Heart Rates: n 5 10, 5 175, s 5 15 Electric Snow Thrower Maximum Heart Rates: n 5 10, 5 124, s 5 18

a. Find the 95% confidence interval estimate of the population mean for those people who shovel snow manually.

b. Find the 95% confidence interval estimate of the population mean for those people who use the electric snow thrower.

c. If you are a physician with concerns about cardiac deaths fostered by manual snow shoveling, what single value in the confidence interval from part

(a) would be of greatest concern?

d. Compare the confidence intervals from parts

(a) and

(b) and interpret your findings.