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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