Question

A, B and C can do a piece of work in 12 days, 14 days and 16 days respectively. All three of them started the work together and after working for four days C leaves the job, B left the job 4 days before completion of the work. Find the approximate time required to complete the work. (in days)

• A. 9 days
• B. 11 days
• C. 8 days
• D. 7 days

Answer 1

Answer:

D. 7 days

The time is taken by A to complete the work = 12 days The time is taken by B to complete the work = 14 days The time is taken by C to complete the work = 16 days The total amount of work = L.C.M of (12, 14 and 16) = 336 units Efficiency of A =336/12 = 28 Efficiency of B = 336/14 = 24 Efficiency of C = 336/16 = 21 28x + 21(4) + 24(x - 4) = 336 28x + 84 + 24x - 96 = 336 52x - 12 = 336 52x = 336 + 12 = 348 52x = 348 x ≈ 7 days