To estimate the average service time at a hamburger fast-food restaurant, a management
consultant noted the times that it took for 35 counter persons, a random sample, to complete a
standard order. It took, on average, 72.2 seconds with a standard deviation of 12.8 seconds to
complete the orders.
a)
What can the consultant assert with 95% confidence about the maximum error, if he uses
X bar = 72.2 seconds as an estimate of the true average time to complete a standard order?
b)
Construct a 95 percent confidence interval for the true average time that it takes a counter
person to complete the standard order/
