Residents of Hawaii have the longest life expectancies, averaging 81.48 years (www.worldlifeexpectancy.com, data retrieved June 4, 2012). A sociologist collects data on the age at death for 50 recently deceased Michigan residents. A portion of the data is shown in the accompanying table; the complete data set, labeled MI_Life_Expectancy, can be found on the text website.

Assume that the population standard deviation is 5 years.

Age at Death

76.4

76.0

:

73.6

a. Use Excel to construct the 95% confidence interval for the mean life expectancy of all residents of Michigan.

b. Use the 95% confidence interval to determine if the mean life expectancy of Michigan residents differs from that for Hawaii residents.