A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spend studying per week. Based on a simple random sample, they surveyed 45 students. The survey showed that students studied an average of 18 hours per week with a standard deviation of 8 hours.
A national study found that students studied, on average, 15.0 hours.
You hypothesize that students at this university study more than the national average.
What is the standard error of the mean?