posted by Mike .
Recently, a price war has developed among retailers selling Brand X denim jeans. A major chain buyer wishes to estimate the mean price of these jeans during this period to compare it to the normal selling price of $20.00. A random sample of 7 major retailers produces a mean retail price of $13.50 with a standard deviation of $3.50. A 80% confidence interval for the true mean retail price of Brand X jeans during the price war is: