Travel and Transportation

Some municipal managers complain a city bus route is the most difficult service to fulfill. Traffic jams and roadwork are often the cause of unreliable service. In an effort to analyze current city bus transportation in Atlanta, Georgia, a random sample of routes and stops was obtained. The number of minutes the bus was late (compared with the posted route times) was recorded. The resulting data are given in the table below. A value of 0.00 means the bus arrived on time.

a. Assume the underlying distribution of late times is normal. Find a 90% confidence interval for the true mean number of minutes a city bus in Atlanta is late.

b. Use the methods described in Section 6.3, page 272, to determine whether there is any evidence to suggest that the distribution of late times is non-normal.

c. If city buses in Atlanta consistently arrive more than five minutes late, the mayor receives a large number of phone calls from irate citizens. Using your answer to part (a), is there any evidence to suggest the mayor will be receiving nasty phone calls? Justify your answer.