A publisher wants to estimate the mean length of time (in minutes) all adults spend reading newspapers online. To determine this estimate, the publisher takes a random sample of 15 people and obtains the following results:
11, 9, 8, 10, 10, 9, 7, 11, 11, 7, 6, 9, 10, 8, 10
Assume that the population of times is normally distributed. The sample yields a mean of 9.1 and a standard deviation of 1.6.
Use this information for the remaining problems on the final exam.
1.) What is the margin of error for a 90% confidence interval? 26. Construct the 90% confidence interval for the mean population length reading time. Show the work.
2.) Interpret the 90% confidence interval for the mean population length reading time. (Remember, use correct grammar and complete sentences. This is a formal statement.)
3.) How can we reduce the margin of error? Explain.