Help with questions 1-3 please. Thank you.

A professor at a large university believes that her students take an average of 15 credit hours per term. A random sample of 24 students in her class of 250 students reported the number of credit hours they were taking and the mean as 16.6 hours with a standard deviation of 2.22 hours. When viewing a histogram of the data for these 24 students, the professor observed the distribution of credit hours to be unimodal and approximately symmetric. Does this sample indicate that students are taking more credit hours than the professor believes? Test an appropriate hypothesis using the PHANTOMS guide below. P: H: A: N: T: O: M/S: 2. With 90% confidence, between what two values would the true mean of credit hours for this professor's students lie? You do not need to recheck conditions, write a formula, or interpret. 3. What critical value (t*) was used in the calculation for the interval in question 2