The personnel department of a large corporation wants to estimate the family dental expenses of its employees to determine the feasibility of providing a dental insurance plan. For random sample of 100 employees, the average family dental expenses turned out to be $260. The population standard deviation is known to be =$140. Calculate a 90% confidence interval (CI) for the mean family dental expenses. Consider the same problem as above with one exemption: now the number $140 is the standard deviation only for the sample of the 30 people selected (we denoted it by s). We are going to find the CI in this case a. Do you expect the new CI to be wider or narrower than the previous CI in Problem 1? b. Find this CI. Check whether your answer to (a) is correct.