Question

A student group claims that first year students at a university study 2.5 hours (150 minutes) per night during the school week. A skeptic suspects that they study less than that on average. He takes a random sample of 30 first year students and finds that X=137 minutes and sx=45 minutes. A graph of the data shows no outliers but some skewness. Carry out an appropriate significance test at the 5% significance level. What conclusions do you draw?

Answer 1

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.

However, depending on the degree and direction of the skew, the probability may not apply.