A and B can complete work in 9 days, while B and C can complete the same work in 18 days. When working together A, B and C, can finish the same work in 8 days. How many days will it take for A and C to complete the work together?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3. i.e. 12.
Given that
A and B can complete work in 9 days
B and C can complete the same work in 18 days
Together A, B and C, can finish the same work in 8 days
Total work = LCM (9, 18, 8) = 72
The combined efficiency A and B = 72/9 = 8
The combined efficiency B and C = 72/18 = 4
The combined efficiency of A, B, and C = 72/8 = 9
So, the efficiency of A = 9 - 4 = 5
the efficiency of C = 9 - 8 = 1
Hence, A and C can complete the work together in = 72/(5 + 1) = 72/6 = 12 days