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    Computing and applying confidence interval for population mean

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    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

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    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 /√100 = 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.