FILE(Use Excel) An engineer wants to determine the effectiveness of a safety program. He collects annual loss of hours due to accidents in 12 plants "before and after" the program was put into operation. The data can be found on the text website, labeled Safety Program.

Plant Before After Plant Before After 1 100 98 7 88 90 2 90 88 8 75 70 3 94 90 9 65 62 4 85 86 10 58 60 5 70 67 11 67 60 6 83 80 12 104 98

a. Specify the competing hypotheses that determine whether the safety program was effective.

b. Assuming that hours are normally distributed, calculate the value of the test statistic.

c. At the 5% significance level, calculate the critical value(s).

d. Is there sufficient evident to conclude that the safety program was effective? Explain. PG-69