Airline mergers are sometimes followed by a decrease in performance, as operations are rationalized and staff adjusts to new operating protocols. One measure of airline efficiency is the percentage of on-time departures. Before a recent merger, Northeast Airlines took a random sample of 100 flights, and found that 85 of them had departed on time. After the merger, a sample of 100 flights showed that 78 had departed on time. At the 4% level of significance, is there evidence that the proportion of on-time flights decreased after the merger? The airline handles thousands of flights every day.