Topic Interval Estimates SHOW YOUR SOLUTIONS

1. A company wants to know the average time an employee spends in the restroom. A previous study showed that the standard deviation is 5 minutes. How large should a sample be taken to be 95% confident that a sample mean should be 0.8 minutes from the true mean? 2. A statistics teacher wishes to estimate the average number of minutes students spend traveling to school every day. The standard deviation from a previous study is 4.3 minutes. How large a sample must be selected if he wants to be 99% confident of finding whether the true mean differs from the sample mean by 1 minute