Costco installs automobile tires on a first-come first-serve basis. The total time a customer needs to wait for the installation to be completed follows the normal distribution with a mean time of 106.3 minutes and a standard deviation of 18.5 minutes. The interval around the mean that contains 68% of the wait time for customers is -----.

Question

Quizplus · Accepted Answer

The interval that contains 68% of the wait time for customers in a normal distribution is defined by one standard deviation above and below the mean. Therefore, the interval is calculated as mean - standard deviation to mean + standard deviation: 106.3 - 18.5 = 87.8 and 106.3 + 18.5 = 124.8.

Costco Installs Automobile Tires on a First-Come First-Serve Basis