You have recorded the time slept on a Tuesday and the time slept on a Sunday for a random sample of 15 students. You want to investigate whether students tend to sleep more on weekends than on weekdays. Which test(s) can you use? Answer for each circumstance.

a. Assume the distribution of sleep hours for both Tuesday and Sunday are approximately Normal.

b. Assume the distribution of sleep hours for both Tuesday and Sunday are not approximately Normal and assume that the distribution of differences in sleep hours for each student is not Normal.

c. Assume the distributions of sleep hours for both Tuesday and Sunday are not Normal but assume the distribution of the differences in sleep hours is approximately Normal.

Choose from the following tests, as appropriate: paired t-test, sign test, two-sample t test, and Mann-Whitney test. There may be two acceptable choices.