The Boston Public School District Has Had Difficulty Maintaining On-Time

Multiple Choice

The Boston public school district has had difficulty maintaining on-time bus service for its students ("A Year Later, School Buses Still Late," Boston Globe, October 5) . Suppose the district develops a new bus schedule to help combat chronic lateness on a particularly woeful route. Historically, the bus service on the route has been, on average, 12 minutes late. After the schedule adjustment, the first 36 runs were an average of eight minutes late. As a result, the Boston public school district claimed that the schedule adjustment was an improvement-students were not as late. Assume a population standard deviation for bus arrival time of 12 minutes. Which of the following can be used to determine whether the schedule adjustment reduced the average lateness time of 12 minutes?

A) H₀: μ = 8, H_A: μ ≠ 8
B) H₀: μ < 12, H_A: μ ≥ 12
C) H₀: μ ≥ 12, H_A: μ < 12
D) H₀: ≥ 8, H_A: < 8