1) According to the National Survey of Student Engagements findings, the average student spends about 17 hours each week preparing for classes. Preparation for classes includes homework, reading and any other assignments.Assume the standard deviation of time spent preparing for class is 4 hours. If you select a random sample of 16 students:

1) What is the probability that the mean time spent preparing for the classes is at least 16 hours per week?

2) Their is an 85% chance that the sample mean is less than how many hours per week?

3)What assumption must you make in order to solve a and b?