Astationery store wants to estimate the mean retail value of greeting cards that it has in its inventory. a random sample of 100 greeting cards indicates a mean value of $2.55 and a standard deviation of $0.44.a. asumming a normal distribution, construct a 95% confidence interval estimate of the mean value of all greeting cards in the store's inventory. b. suppose there were 2,500 greeting cards in the store's inventory. how are the results in (a) useful in assisting the store owner to estimate the total value of her inventory?