Part A.

A sample of 30 patients in a doctor's office showed that they had to wait for an average of 34 minutes before they could see the doctor. The sample standard deviation is 14 minutes. Assume the population of waiting times is normally distributed.

At 90% confidence, compute the lower bound of interval estimate for the average waiting time of all the patients who visit this doctor.

B.

A university planner wants to determine the proportion of spring semester students who will attend summer school. She surveys 50 current students discovering that 17 will return for summer school.

At 90% confidence, compute the margin of error for the estimation of this proportion.

Part C.

A university planner wants to determine the proportion of spring semester students who will attend summer school. She surveys 42 current students discovering that 17 will return for summer school.

At 90% confidence, compute the lower bound of the interval estimate for this proportion.