At a local restaurant, the amount of time that customers have to wait for their food is normally distributed with a mean of 26 minutes and a standard deviation of 5 minutes. Using the empirical rule, what percentage of customers have to wait between 21 minutes and 31 minutes?

99.7% of customers have to wait between 8 minutes to 30 minutes for their food.

Step-by-step explanation:

We are given the following in the question:

Mean, μ = 18 minutes

Standard Deviation, σ = 4 minutes

We are given that the distribution of the amount of time is a bell-shaped distribution that is a normal distribution.

Empirical Formula:

Almost all the data lies within three standard deviations from the mean for normally distributed data.

About 68% of data lies within one standard deviation from the mean.

About 95% of data lies within two standard deviations of the mean.

About 99.7% of data lies within three standard deviations of the mean.

Thus, 99.7% of the customers have to wait:

μ-3σ = 18 - 3(4) = 6

μ-3σ = 18 + 3(4) = 30

Thus, 99.7% of customers have to wait between 8 minutes to 30 minutes for their food.

Hope this helps!! :D