Question

A can do a piece of work in 30 days, while B alone can do it in 40 days. In how many days can A and B working together do it?

• A. 17 and 1/7
• B. 27 and 1/7
• C. 42 and 3/4
• D. 70

Answer 1

Answer:

A. 17 and 1/7

The LCM of (30 , 40) = 120 Total work = 1120 unit Efficiency of A = 120/30 = 4 Efficiency of B = 120/40 = 3 Efficiency of A + B = 4 + 3 = 7 Time taken by A and B to complete the work = 120/7 = 17 1/7 days