Reasons for being late, part 2.

Using the results of the survey described in Exercise 63, does it show that the mean duration of students being late for class due to overlooking their timetables is less than that of them being late due to oversleeping?

a) Test an appropriate hypothesis, and state your conclusion.

b) If you concluded there is a difference, estimate the size of that difference with a 90% confidence interval, and explain what your interval means.