Each of the three people individually can complete a certain job in 4, 5, and 8 hours, respectively. What is the lowest fraction of the job that can be done in 1 hour by 2 of the people working together at their respective rates?  Choose the most appropriate option: A) 9/20 B) 11/20 C) 11/32 D) 13/40 E) 17/40
The two slowest people work at rates of 1/5 and 1/8 of the job per hour.   The sum of these rates is 1/5 + 1/8 = 13/40 of the job per hour.   The answer is 13/40.
<result>D</result>
Each of the three people individually can complete a certain job in 4, 5, and 8 hours, respectively. What is the lowest fraction of the job that can be done in 1 hour by 2 of the people working together at their respective rates?