Each of the three people individually can complete a certain job in 3, 4, and 6 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) 1 / 3	B) 9 / 20	C) 8 / 15	D) 5 / 12	E) 2 / 3

Rationale: the two slowest people work at rates of 1 / 4 and 1 / 6 of the job per hour . the sum of these rates is 1 / 4 + 1 / 6 = 5 / 12 of the job per hour . the answer is d .
Answer: D