A can do 4/5 of a work in 20 days and B can do 3/4 of the same work in 15 days. They work together for 10 days. C alone completes the remaining work in 1 day. B and C together can complete 3/4 of the same work in:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 5 days
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Understanding |
Application |
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A can do 4/5 of a work in 20 days and B can do 3/4 of the same work in 15 days. |
So, Time in which A can complete the work = 20 × 5/4 = 25 days And Time in which B can complete the work = 15 × 4/3 = 20 days |
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Suppose total work = 100 units (LCM of 25 and 20) |
So, Efficiency of A = 100/25 = 4 Efficiency of B = 100/20 = 5 |
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Work done by A and B in 10 days = 10 × (4 + 5) = 90 units |
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Remaining work = 100 – 90 = 10 units |
C alone completes the remaining work in 1 day. So, Efficiency of C = 10/1 = 10 |
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(3/4)th of the work = 100 × 3/4 = 75 units |
So, Time in which B and C can complete 75 units of work = 75/(10 + 5) = 5 days |