Question: The National Quality Research Center

The National Quality Research Center at the University of Michigan provides a quarterly measure of consumer opinions about products and services (The Wall Street Journal, February 18, 2003). A survey of 10 restaurants in the Fast Food/ Pizza group showed a sample mean customer satisfaction index of 71. Past data indicate that the population standard deviation of the index has been relatively stable with σ=5.

a. Explain what assumption the researcher should be willing to make if a margin of error is desired.

b. Using 95% confidence, determine the margin of error.

c). Determine the margin of error if 99% confidence is desired.