Bank of America's Consumer Spending Survey collected data on
annual credit card charges in seven different categories of
expenditures: transportation, groceries, dining out, household
expenses, home furnishings, apparel, and entertainment (U.S.
Airways Attache, December 2003). Using data from a sample of 42
credit card accounts, assume that each account was used to identify
the annual credit card charges for groceries (population 1) and the
annual credit card charges for dining out (population 2). Using the
difference data, the sample mean...