A postal worker can sort a day's worth of mail in 8 hours. With her supervisor helping, it takes 3 hours. How long would it take the supervisor working alone?
A) 4 hrs. 48 min.
B) 5 hrs. 20 min.
C) 2 hrs. 11 min.
D) 3 hrs. 50 min.

Question

Quizplus · Accepted Answer

The postal worker can sort the mail in 8 hours, meaning her rate is 1/8 of the mail per hour. Together, they can sort the mail in 3 hours, meaning their combined rate is 1/3 of the mail per hour. To find the supervisor's rate, subtract the worker's rate from the combined rate: 1/3 - 1/8 = 8/24 - 3/24 = 5/24. This means the supervisor can sort the mail alone in 24/5 hours, which is 4 hours and 48 minutes.

A Postal Worker Can Sort a Day's Worth of Mail