Question

At a local restaurant, the amount of time that customers have to wait for their food is normally distributed with a mean of 20 minutes and a standard deviation of 2 minutes. Using the empirical rule, what percentage of customers have to wait between 14 minutes and 26 minutes?

Answer 1

14 minutes and 26 minutes are 20 ± 6, which is ±3 standard deviations (6/2 = 3). By the empirical rule about 99.7% of observations lie within ±3σ, so approximately 99.7% of customers.