To do a certain work, the ratio of efficiencies of X and Y is 5 : 7. Working together, X and Y can complete the same work in 70 days. X alone started the work and left after 42 days. Y alone will complete the remaining work on :
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 90 days.
Efficiencies ratio X to Y = 5 ∶ 7
Total work = (5 + 7) × 70 = 840
Work done by X in 42 days = 42 × 5 = 210
Remaining work = 840 – 210 = 630
Remaining work completed by Y in = 630/7 = 90 days