How to find the 95% confidence interval for the true population mean.
A stationery store needs to estimate the mean retail value of greeting cards that it has in its inventory. A random example of 100 greeting cards indicates a mean value of $2.55 and a standard deviation of $0.44.
1) Presuming a normal distribution construct a 95% confidence interval estimate of the mean value of all greeting cards in the store inventory.
2) Presume there were 2500 greeting cards in the store inventory. Explain how are the results in (a) useful in assisting the store owner to estimate the total value of her inventory?