An art dealer wants to estimate the average value of works of art of a certain period

Question:

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% confidence interval for the average value of all works of art of this kind.

Dealer
A dealer in the securities market is an individual or firm who stands ready and willing to buy a security for its own account (at its bid price) or sell from its own account (at its ask price). A dealer seeks to profit from the spread between the...