Aclass survey in a large class for first-year college students asked, "about how many minutes do you study on a typical weeknight? " the mean response of the 253 students was x⎯⎯⎯ = 150 minutes. suppose that we know that the study time follows a normal distribution with standard deviation σ = 65 minutes in the population of all first-year students at this university. use the survey result to give a 95% confidence interval for the mean study time of all first-year students.