In How Much Time They can do it Together? if

A is thrice as good a workman as B and is therefore able to finish a piece of work in 60 days less than B. Find the time in which they can do it, working together.

  1. 23/2 days
  2. 45/2 days
  3. 21 days
  4. 25 days
Desire Adnan Default Asked on 3rd August 2015 in Maths.
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  • 1 Answer(s)

    Answer: (2) 45/2 days
    Explanation:-
    Let the B can complete the work = X days
    Then, A can complete the work = (X – 60 ) days

    The ratio of work done by A and B = 3 : 1
    Then,
    (X – 60 )/X = 1/3
    By cross multiplication,
    3 X – 3 x 60 = X
    3 X – X = 180
    2 X = 180
    X = 180/2
    X = 90
    Therefore, time taken by B  to complete the work = 90 days
    Then, time taken by A to complete the work = 90 /3
    = 30 days
    A  & B work together ,
    Then, they will complete the work = 90 x 30/(90 + 30)
    = 2700/120
    = 45/2 days
    Hence, the answer is (2) 45/2 days.

    Anurag Mishra Professor Answered on 3rd August 2015.
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