Final answer:
When testing a claim that the mean difference for a population is greater than 0 with a sample of 12 pairs and a significance level of 0.05, a right-tailed test is used to reject the null hypothesis.
Step-by-step explanation:
When testing a claim that the mean difference for a population is greater than 0 with a sample of 12 pairs and a significance level of 0.05, a right-tailed test is used to reject the null hypothesis. The criterion for rejecting the null hypothesis is that the p-value should be less than the significance level.
In this case, the p-value is 0.0004, which is less than the significance level of 0.05. Therefore, we would reject the null hypothesis and conclude that there is enough evidence to support the claim that the mean difference for the population is greater than 0.