Question

Question 6

A random sample of 13 DVD movies had a mean length of 115.1 minutes, with a standard deviation of 64.7 minutes. Find the lower bound of the 90% confidence interval for the true mean length of all Hollywood movies. Assume movie lengths to be approximately normally distributed.

Round to one decimal place (for example: 108.1). Write only a number as your answer. Do not write any units.

Question 7

Six measurements were made of the mineral content (in percent) of spinach, with the following results. It is reasonable to assume that the population is approximately normal.

19.1, 20.1, 20.8, 21.2 , 20.5, 19.6

Find the lower bound of the 95% confidence interval for the true mineral content.

Round to three decimal places (for example: 20.015). Write only a number as your answer. Do not write any units.

Question 8

Following are interest rates (annual percentage rates) for a 30-year-fixed-rate mortgage from a sample of lenders in a certain city. It is reasonable to assume that the population is approximately normal.

4.327, 4.461, 4.547, 4.801 , 4.365, 4.428 , 4.842

Find the upper bound of the 99% confidence interval for the mean rate.

Round to three decimal places (for example: 4.015). Write only a number as your answer. Do not write any units.

Answer 1