The ratio of the efficiencies of A, B and C, to do a certain work is 7 : 3 : 5. Working together, they can complete the work in 21 days. A and C worked together for 15 days. The remaining work will be completed by B alone in?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 45 days
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Understanding |
Application |
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Given Ratio of efficiencies of A, B and C = 7 : 3 : 5 Suppose the efficiencies are 7x, 3x and 5x respectively. Since together they can complete the work in 21 days: Hence, Total work = (7x + 3x + 5x) × 21 = 15x × 21 = 315x |
A and C worked together for 15 days: Work done = (7x + 5x) × 15 = 12x × 15 = 180x Hence, remaining work = 315x – 180x = 135x Since B does the remaining work alone: Time taken by B = 135x/3x = 45 day |