3. A random sample of 81 credit sales in a department store showed an average sale...

3. A random sample of 81 credit sales in a department store showed an average sale of $68.00. From past data, it is known that the standard deviation of the population is $27.00.

a. First, verify that the Central Limit Theorem condition(s) have been met, then construct a 90% confidence interval of the population mean.

b. Construct a 99% confidence interval of the population mean.

c. Justify in your own words the difference in the interval lengths from parts a & b. (i.e. why are they different?)

d. Generally speaking, if the sample size is increased, what impact does it have on the margin of error? On the confidence interval?

e. What would be the minimum sample size, at 95% confidence, if we want the Margin of Error to be 5?

Expert Solution

orchestra answered 2 years ago

A random sample of 81 credit sales in a department store showed an average sale of...

A random sample of 81 credit sales in a department store showed an average sale of $68.00. From past data, it is known that the standard deviation of the population is $27.00. What is the 99% confidence interval of the population mean? (Round to two decimal places)

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