A random sample of 49 lunch customers was taken at a restaurant. ...

[SGallaher96]

A random sample of 49 lunch customers was taken at a restaurant. The average amount of time these customers stayed in the restaurant was 45 minutes with a standard deviation of 14 minutes.
 a. Compute the standard error of the mean.
  b. With a .95 probability, what statement can be made about the size of the margin of error?
  c. Construct a 95 confidence interval for the true average amount of time customers spent in the restaurant.
  d. With a .95 probability, how large of a sample would have to be taken to provide a margin of error of 2.5 minutes or less?

Question 2

A production process that is in control has a mean () of 200 and a standard deviation () of 22. Determine the lower and the upper control limits for sample sizes of 49.

[Bsand8]

Answer to Question 1

a. 2
b. There is a .95 probability that the sample mean will provide a margin of error of 4.022 minutes or less.
c. 40.98 to 49.02 minutes (rounded)
d. 121

Answer to Question 2

LCL = 190.571
UCL = 209.429