A can do as much work as B and C together can. A and B together can do a piece of work in 7 hours and 12 minutes, and C can do it in 36 hours. Find the time (in hours) that B needs to do the work alone.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 18 hours
Given that
A can do as much work as B and C together can, which means
The efficiency of A is equal to the combined efficiency of B and C.
A = B + C........ (1
According to the question
(A + B) × 432 = C × 36 × 60
A + B = 5C ......... (2
After solving the equations
2A = 6C
A = 3C
B = 2C
The efficiencies of A, B and C are 3, 2, and 1, respectively.
Hence, B can do the work alone = 36/2 = 18 hours