The on time performances of flights in the airline industry are an important measurement that can help attract customers. The following data show the number of late flights from random samples taken from United Airlines and Southwest Airlines:

United                                                 Southwest

x₁ = 130 ……………..             x₂ = 119

n₁ = 175 ……………..            n₂ = 140

a. Perform a hypothesis test using α = 0.05 to determine if the on time performances of these two airlines are different.

b. Determine the p value and interpret the results.

c. Construct a 95% confidence interval to estimate the difference in the on time performances of these two airlines.

d. Verify your results using PHStat.