Dullco Manufacturing Claims That Its Alkaline Batteries Last at Least

Multiple Choice

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player. But tests on a random sample of 18 batteries from a day's large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours. In a left-tailed test at α = .05, which is the most accurate statement?

A) We would strongly reject the claim.
B) We would clearly fail to reject the claim.
C) We would face a rather close decision.
D) We would switch to α = .01 for a more powerful test.