1. An art dealer wants to estimate the average value of works of art of a certain period and type. A random sample of 20 works of art is appraised. The sample mean is found to be $5,139 and the sample standard deviation $640. Give a 95% con?- dence interval for the average value of all works of art of this kind.
2. A management consulting agency needs to estimate the average number of years of experience of executives in a given branch of management. A random sample of 28 executives gives x = 6.7 years and s = 2.4 years. Give a 99% con?dence interval for the average number of years of experience for all executives in this branch.