Question: Question 1:

A city planner working on bikeways designs a questionnaire to obtain information about local bicycle commuters. One of the questions asks how long it takes the rider to pedal from home to his or her destination. A random sample of 22 local bicycle commuters yields a mean of 25.82 minutes and a standard deviation of 7.71 minutes.

(a) Find a 90% confidence interval for the mean commuting time of bicycle commuters.

(b) Explain in one sentence how to interpret this confidence interval to someone with no training in statistics.

(c) If we wanted to estimate the true mean within 4 minutes from the population mean, with a confidence level of 95%, how large a sample would be required?