Question

You wanted to estimate the mean number of vehicles crossing a busy bridge in your neighborhood each morning during rush hour for the past year. To accomplish this, you stationed yourself and a few assistants at one end of the bridge on 21 randomly selected mornings during the year and counted the number of vehicles crossing the bridge in a 10-minute period during rush hour. You found the mean to be 138 vehicles per minute, with a standard deviation of 28.

(a) Construct the 95% confidence interval for the population mean (vehicles per minute).


(b) Construct the 99% confidence interval for the population mean (vehicles per minute).

Answer 1