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 5,2011) .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.The value of the test statistic is ____________.

A) t₃₅ = -2.00
B) z = -2.00
C) t₃₅ = -0.33
D) z = -0.33