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Among 4 persons A, B, C and D. A takes twice as much time as B to complete a piece of work. B takes twice as much time as C and C takes twice as much time as D to complete the same work. If three of them taken as one group and another three as another group, then ratio of time taken to do the work = 13:7. Find the first group ?

Attempt:

Ratio of time taken by A, B, C , D is 8:4:2:1

Therefore ratio pf their efficiencies is 1:2:4:8

Combined efficiency of ABC=7

Combined efficiency of ACD=13

amWhy
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Soumee
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1 Answers1

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The answer to the question, which wasn't really specified in your answer, is ABC. The efficiency is really the rate at which each group works. The slower group ABC taking 13 time units compared to 7 time units for the faster group ACD to complete the same work.

Phil H
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  • Even I thought thought that ABC is the answer. However, ACD was mentioned as the answer in the book, hence I got confused. – Soumee Jun 03 '18 at 17:44
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    Then you thought right. ABC takes longer than ACD so the answer in the book isn't correct......not an uncommon occurrence unfortunately. – Phil H Jun 03 '18 at 17:54