A can do a certain piece of work in 20 days. B is 25% more efficient than A, and C is 20% more efficient than B. A and C work together for 5 days. B alone will complete the remaining work in:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 6 days.
Calculations:
Efficiency of B is 25% more than A
Ratio of efficiency = A : B = 4 : 5
Efficiency of C is 20% more than B
Ratio of efficiency = B : C = 5 : 6
Ratio of efficiency of A, B and C = 4 : 5 : 6
Total work = 20 × 4 = 80 units
Work done by A and C in 5 days = (4 + 6) × 5 = 50 units
Remaining work = 80 - 50 = 30 units
B complete the remaining work = 30/5 = 6 days