In Melanie's Styling Salon, the time to complete a simple haircut is normally distributed with a mean of 25 minutes and a standard deviation of 4 minutes. The slowest quartile of customers will require longer than how many minutes for a simple haircut? A)3(n + 1)/4 minutes B)26 minutes C)25.7 minutes D)27.7 minutes Using Excel =NORM.INV(.75,25,4) = 27.698, or Q₃ = 25 + 0.675(4) = 27.7 using AppendixC.

Question

Quizplus · Accepted Answer

To find the time required for the slowest quartile of customers, we need to find the value that corresponds to the 75th percentile of the normal distribution with a mean of 25 minutes and a standard deviation of 4 minutes. Using a calculator or Excel function NORM.INV, we get the answer as 27.698 or rounded to the nearest minute as 28. This means that the slowest quartile of customers will require longer than 27.7 minutes (rounded to one decimal place) or 28 minutes (rounded to the nearest minute). Therefore, the best choice is D, which gives the answer as 27.7 minutes.

In Melanie's Styling Salon, the Time to Complete a Simple