The American Bankers Association collects data on the use of credit cards, debit cards, personal checks, and cash when consumers pay for in-store purchases (The Wall Street Journal, December 16, 2003). In 1999, the following usages were reported.

In Store Purchase Percentage

Credit Card= 22%

Debit Card= 21%

Personal Check= 18%

Cash= 39%

A sample taken in 2003 found that for 220 in-stores purchases, 46 used a credit card, 67 used a debit card, 33 used a personal check, and 74 used cash.

a. At a=.01, can we conclude that a change occurred in how customers paid for in-store purchases over the four year period from 1999 to 2003? What is the p-value?

b. Compute the percentage of use for each method of payment using the 2003 sample data. What appears to have been the major change or changes over the four year period?

c. In 2003, what percentage of payments was made using plastic (credit card or debit card)?