In an effort to reduce energy costs, a major university hasinstalled more efficient lights as well as automatic sensors thatturn the lights off when no movement is present in a room.Historically, the cost of lighting an average classroom for 1 weekhas been $265. To determine whether the changes have signficantlyreduced costs, the university takes a sample of 50 classrooms. Theyfind that the average cost for 1 week is $247 with a standarddeviation of $60. When testing the hypothesis (at the 5% level ofsignificance) that the average energy use has decreased from thepast, what is the test statistic? (please round your answer to 2decimal places)
