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12 Sep 2019, 19:13
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D
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Difficulty:
95%
(hard)
Question Stats:
50% (02:43) correct
50%
(03:18)
wrong
based on 84
sessions
History
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Working alone, B needs 50% more time to complete a certain job than A does. A and B completes the same job in 15 days in the following manner: A works alone till half the job is done, then A and B work together for 2 days, and finally B works alone to complete the remaining 10% of the job. In how many days can B alone complete the entire job ?
A. 16
B. 20
C. 24
D. 30
E. 36
A. 16
B. 20
C. 24
D. 30
E. 36
12 Sep 2019, 19:30
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Dillesh4096
So, we know that B takes 50% more time..
If A does it in A days, B will take 1.5A days...
A and B completes the same job in 15 days in the following manner:
1) A works alone till half the job is done,...... so time taken is \(\frac{A}{2}\)
2) then A and B work together for 2 days,..... so time taken is 2 days
3) and finally B works alone to complete the remaining 10% of the job, ..... as B days for 100%, so \(\frac{B}{10}\)days =\(\frac{1.5A}{10}\)
Adding all three \(\frac{A}{2}+2+\frac{1.5A}{10}=15......\frac{6.5A}{10}=15-2=13....A=\frac{13*10}{6.5}=20\).
A is 20, and, thus, B becomes 1.5*20=30.
D
General Discussion
23 Sep 2019, 11:48
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I tried to solve it through different ways.
B takes 50% more time means ratio of efficiency of A to B is 3:2.
Now 50/3x+2+10/2x =15
Solving it, we get x= 10/6
Efficiency of B =20/6
Time taken by B to complete entire work =100*6/20=30 days.
But
When I tried to equate 40% of work done in 2 days to efficiency i got wrong answer.
40/5x=2.
Kindly help
Posted from my mobile device
B takes 50% more time means ratio of efficiency of A to B is 3:2.
Now 50/3x+2+10/2x =15
Solving it, we get x= 10/6
Efficiency of B =20/6
Time taken by B to complete entire work =100*6/20=30 days.
But
When I tried to equate 40% of work done in 2 days to efficiency i got wrong answer.
40/5x=2.
Kindly help
Posted from my mobile device
