6. The Bureau of Transportation tracks the flight arrival performances of the 10 biggest airlines in the United States (The Wall Street Journal, March 4, 2003). Flights that arrive within 15 min- utes of schedule are considered on time. Using sample data consistent with Bureau of Trans- portation statistics reported in January 2001 and January 2002, consider the following: January 2001 A sample of 924 flights showed 742 on time. January 2002 A sample of 841 flights showed 714 on time.

a. What is the point estimate of on-time flights in January 2001?

b. What is the point estimate of on-time flights in January 2002?

c. Let p, denote the population proportion of on-time flights in January 2001 and p2 de- note the population proportion of on-time flights in January 2002. State the hypothe- ses that could be tested to determine whether the major airlines improved on-time flight performance during the one-year period.

d. What is the p-value? At a = .05, what is your conclusion?