Before changes to its management staff, an automobile assembly line operation had a scheduled mean completion time of13.4

minutes. The standard deviation of completion times was1.8

minutes. An analyst at the company suspects that, under new management, the mean completion time,

,is now less than13.4

minutes. To test this claim, a random sample of24

completion times under new management was taken by the analyst. The sample had a mean of12.6

minutes. Assume that the population is normally distributed. Can we support, at the0.05

level of significance, the claim that the population mean completion time under new management is less than13.4

minutes? Assume that the population standard deviation of completion times has not changed under new management.

Perform a one-tailed test. Then complete the parts below.

Carry your intermediate computations to three or more decimal places, and round your responses as specified below. (If necessary, consult alist of formulas.)

(a)State the null hypothesisH

0

and the alternative hypothesisH

1

.H

0

:

H

1

:

(b)Determine the type of test statistic to use.

(Choose one)

(c)Find the value of the test statistic. (Round to three or more decimal places.)

(d)Find thep-value. (Round to three or more decimal places.)

(e)Can we support the claim that the population mean completion time under new management is less than13.4

minutes?YesNo