Question

a)A sample of 30 patients in a doctor's office showed that they had to wait for an average of 33 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 44 current students discovering that 17 will return for summer school.At 90% confidence, compute the lower bound of the interval estimate for this proportion.

C)In order to estimate the average electric usage per month, a sample of 42 houses were selected and the electric usage determined. The sample mean is 2,000 KWH. Assume a population standard deviation of 100 kilowatt hours. At 99% confidence, compute the upper bound of the interval estimate for the population mean.

Answer 1

Solution-

a) At 90% confidence,  the lower bound of interval estimate for the average waiting time of all the patients who visit this doctor is-

28.657

• Calculations

b)At 90% confidence, the lower bound of the interval estimate for this proportion-

0.266

• Calculations-

c)At 99% confidence, the upper bound of the interval estimate for the population mean-

2039.746

• Calculations-