A works twice as fast as B. If B can complete a work in 12 days independently then the number of days in which A and B can together finish the work is ?

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4 days

6 days

8 days

18 days.

answer is A.

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Detailed Solution

Concept: Work and time. Time and work concerns the simultaneous performance of an individual or a group's productivity and the amount of time required for them to finish a task. Work is the energy expended to complete a task or produce a deliverable.
Given:[10]
i. A works twice as fast as B.
ii. Time taken by B to finish work independently= 12 days
To find: A and B can together finish the work.
As per question, A works twice as B which means the ratio of efficiency of A to B is 2:1. ${"mathml":"<math class="image_resized" style="width:24px;height:36px"><span style="font-family:$ B takes 12 days to finish the work, thus one day work of B = ${"mathml":"<math class="image_resized" style="width:80px;height:36px"><span style="font-family:$ A works twice as fast as B, thus one day work of A = Now if A and B work together than one day work