a-manufacturer-claims-that-the-average-battery-life-of-their-aa-batteries-is-at-

Question

A manufacturer claims that the average battery life of their AA batteries is at least $5.2$ hours. A consumer group tests a random sample of $12$ batteries and finds a mean battery life of $4.9$ hours. Assume the population standard deviation is $0.6$ hours, and battery life is normally distributed. At the $0.01$ significance level, can you reject the manufacturer’s claim?

Accepted Answer

Fail to reject $5.2$ ; there is not enough evidence to say the average battery life is less than $5.2$ hours.

Answer

Reject $5.2$ ; the average battery life is exactly $5.2$ hours.

Answer

Fail to reject $5.2$ ; the average battery life is more than $5.2$ hours.

Answer

Reject $5.2$ ; the battery life is significantly less than $5.2$ hours.