In the past, the mean running time for a certain type of flashlight battery has been 8.5 hours.The manufacturer has introduced a change in the production method and wants to perform a hypothesis test to determine whether the mean running time has changed as a result.This test is:
A)Upper-tailed
B)Lower-tailed
C)Two-sided

Question

Quizplus · Accepted Answer

The manufacturer wants to determine if the mean running time has changed, which means they are interested in finding out if the new mean is either greater than or less than the previous mean of 8.5 hours. This requires a two-sided hypothesis test because they are looking for a difference in either direction (increase or decrease) from the original mean.

In the Past, the Mean Running Time for a Certain