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A is twice as efficient as B. Together they can do a work in 21 days. In how many days will B finish the work?

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A is twice as efficient as B. Together they can do a work in 21 days. In how many days will B finish the work?


1). 54 days
2). 57 days
3). 60 days
4). 63 days


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3 vote
Answered by on | Votes 3 |

Let the number of days in which B finishes the work be ‘d’ days

Given, A is twice as efficient as B

∴ Number of days in whicha A finishes the work = d/2

Given, together they can do a work in 21 days

In 1 day, they together finish 1/21th of the work

∴ 1/d + 2/d = 1/21

⇒ 3/d = 1/21

⇒ d = 63 days

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