Question

A and B can do a work in 12 days, B and C in 15 days and C and A in 20 days. If A, B and C work together, they will complete the work in :

• A. 5 days
• B. 10 days
• C. 12 days
• D. 9 days

Answer 1

Answer:

B. 10 days

A and B can do a piece of work in 12 days. In 1 day, (A+B) can do 1/12th of the work. B and C can do a piece of work in 15 days. In 1 day, (B+C) can do 1/15th of the work. A and C can do a piece of work in 20 days. In 1 day, (A+C) can do 1/20th of the work. (A+B) + (B+C) + (A+C) = 1/12 + 1/15 + 1/20 2 (A+B+C) = 12/60 (A+B+C) = 1/10 In 1 day, (A+B+C) together can do 1/10th of the work. it will take 10 days.