Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 9)
9.
A does 80% of a work in 20 days. He then calls in B and they together finish the remaining work in 3 days. How long B alone would take to do the whole work?
23 days
37 days
37
40 days
Answer: Option
Explanation:
| Whole work is done by A in |  |
20 x | 5 |  |
= 25 days. |
| 4 |
| Now, | |
1 - | 4 | |
i.e., | 1 | work is done by A and B in 3 days. |
| 5 | 5 |
Whole work will be done by A and B in (3 x 5) = 15 days.
| A's 1 day's work = | 1 | , (A + B)'s 1 day's work = | 1 | . |
| 25 | 15 |
 B's 1 day's work = |
|
1 | - | 1 | |
= | 4 | = | 2 | . |
| 15 | 25 | 150 | 75 |
| So, B alone would do the work in | 75 | = 37 | 1 | days. |
| 2 | 2 |
Discussion:
164 comments Page 11 of 17.
Swapraj said:
8 years ago
80%= 4/5.
But, work done by A = 5/4 * 20 why not 4/5 * 20.
Please explain me.
But, work done by A = 5/4 * 20 why not 4/5 * 20.
Please explain me.
Mathi said:
1 decade ago
A = (1/20) * (80/100) = 1/25
1/A + 1/B =1/3(20/100)
1/B=(1/15) - (1/25) =2/75
1/A + 1/B =1/3(20/100)
1/B=(1/15) - (1/25) =2/75
(1)
Charu said:
1 decade ago
Thanks Bhasker, Ganesh and Mini... Keep up the good work!!! cheers
Kriti said:
9 years ago
Hey guys 80/100 = 4/5 then why you people multiplying 5/4 * 20?
Prathap said:
1 decade ago
Bhaskar and rajendra you both are explained very well. Thanks.
Jiya said:
9 years ago
Still, I'm not getting why its 5/4*20? Please explain briefly.
Shefali said:
1 decade ago
How do we get that A & B together can do work in 15 days?
SIVARANJANI said:
1 decade ago
Sorry I can't get it why we should multiply with that 5/4 ?
(2)
Vinoth said:
1 decade ago
@baskar your explations were very nice thank you so much.
Zaidi said:
7 years ago
@Reya.
Take L.C.M of 15 and 25 which comes out to be 75.
Take L.C.M of 15 and 25 which comes out to be 75.
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