Explain why Chebyshev's theorem cannot be used for one standard deviation from the mean.
Question 2
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. Determine the standard error of the mean.
b. With a .95 probability, what can be said about the size of the margin of error?
c. What is the 95 confidence interval of the population mean?