A two-tailed test is conducted at the 5% significance level. What is the right tail percentile required to reject the null hypothesis?

97.5

(Left tail would be 2.5)

In the past, the mean running time for a certain type of flashlight battery has been 8.0 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 increased as a result. The hypotheses are:

To determine the right tail percentile required to reject the null hypothesis in a two-tailed test at the 5% significance level, we need to divide the significance level by 2. In this case, the significance level is 5%, so we divide 5 by 2, which gives us 2.5%.

This means that in order to reject the null hypothesis in the right tail of the distribution, the test statistic must fall in the top 2.5% of the distribution. Therefore, the right tail percentile required to reject the null hypothesis is 2.5%.