Question: Over the last 3 years, Art's Supermarket has observed the following distribution of modes of payment in the express lines: cash (C) 41%, check (CK) 24%, credit or debit card (D) 26%, and other (N) 9%. In an effort to make express checkout more efficient, Art's has just begun offering a 1% discount for cash payment in the express checkout line. The following table lists the frequency distribution of the modes of payment for a sample of 500 express-line customers after the discount went into effect.
Mode of payment C CK D N
Number of customers 240 104 111 45
Test at the 1% significance level whether the distribution of modes of payment in the express checkout line changed after the discount went into effect.