A, B and C can do the same work in 9 days, 12 days and 18 days, respectively. A started the work and worked for 3 days and left. Then, B joined the work and worked for 3 days and left. Then, C joined the work and completed it. Find the number of days C took to complete the work.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. .
Total work = LCM of 9, 12, and 18 = 36
Total work done by A and B = (36/9) × 3 + (36/12) × 3 = 12 + 9 = 21
Remaining work = 36 - 21 = 15
Efficiency of C = 36/18 = 2
Time required for C = 15/2 = days