Airline mergers cause many problems for the airline industry. One variable often quoted as a measure of an airline's efficiency is the percentage of on-time departures. Following the merger of Republic Airlines with Northwest Airlines, the percentage of on-time departures for Northwest planes declined from approximately 85% to about 68%. Suppose that the percentages reported above are based on two random samples of flights: a sample of 100 flights over a period of two months before the merger, of which 85 are found to have departed on time; and a sample of 100 flights over a period of two months after the merger, 68 of which are found to have departed on time. Based on these data, do you believe that Northwest's on-time percentage declined during the period following its merger with Republic?