# Computing and applying confidence interval for population mean

A stationary store wants to estimate the mean retail value of greeting cards that it has in inventory A random sample of 100 greeting cards. a mean value of 2.55 and standard deviation of 0.44

A. Assuming a normal distribution, construct a 95% confidence interval estimate for the mean value of all greeting cards in the store inventory

B. Suppose there are 2500 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 the inventory

https://brainmass.com/statistics/confidence-interval/computing-applying-confidence-interval-population-mean-574780

#### Solution Preview

(A) We are given that n=100, xbar = 2.55, sd=0.44 and level=0.95

Standard Error, SE = sd/sqrt(n)=0.44 /âˆš100 = 0.044

z- score = 1.96 from standard normal table ...

#### Solution Summary

The solution gives detailed steps on calculating confidence interval for population mean. All the formula and calcuations are shown and explained.