According to a marketing research study, American teenagers watched 14.8 hours ofsocial media postspermonth last year, on average. A random sample of 11 American teenagers was surveyed and the mean amount of time permonth each teenager watched social media postswas 15.6. This data has a sample standard deviation of 2.5. (Assume that the scores are normally distributed.)

Researchers conducta one-mean hypothesisat the 5% significance levelto test if the mean amount of time American teenagers watch social media posts permonth is greater than the mean amount of time last year.

The null and alternative hypotheses are H0:=14.8; Ha:>14.8, which is a right-tailed test.