Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 1)
1.
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
Answer: Option
Explanation:
| A's 1 day's work = | 1 | ; |
| 15 |
| B's 1 day's work = | 1 | ; |
| 20 |
| (A + B)'s 1 day's work = |  |
1 | + | 1 |  |
= | 7 | . |
| 15 | 20 | 60 |
| (A + B)'s 4 day's work = | |
7 | x 4 | |
= | 7 | . |
| 60 | 15 |
| Therefore, Remaining work = | |
1 - | 7 | |
= | 8 | . |
| 15 | 15 |
Discussion:
344 comments Page 7 of 35.
Shro said:
1 decade ago
Thanku Prakash :).
Rinkesh said:
1 decade ago
Very simple,
15+20=35
15*20=300
35/300=7/60
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
15+20=35
15*20=300
35/300=7/60
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
Manoj said:
1 decade ago
Can you explain how did 7/60 come?
Manoj said:
1 decade ago
35/300=7/60 please explain it.
Thyag said:
1 decade ago
Hi Manoj,
You need to simplify big number 35/300 in to small number for further calculation.
So, you need to divide one common number of both numerator and denominator.
You couldn't select 2, 3 and 4 as a dividing number. But you can use 5 as a common divider.
If you divide 5 in both numerator and denominator, you will get 7/60.
I hope your doubt clarified.
You need to simplify big number 35/300 in to small number for further calculation.
So, you need to divide one common number of both numerator and denominator.
You couldn't select 2, 3 and 4 as a dividing number. But you can use 5 as a common divider.
If you divide 5 in both numerator and denominator, you will get 7/60.
I hope your doubt clarified.
Anshu said:
1 decade ago
"A" can can do a work in 15 days therefore he did 1/15 of the work in a day.
"B" can do the same work in 20 days therefore he did 1/20 of the work in a day.
Therefore.
[1/15 + 1/20]4 = [4/60 + 3/60]4.
[7/60]4 = 7/15 of the work done.
The total work left = 1 - 7/15 = 15 - 7/ 15 = 8/15.
"B" can do the same work in 20 days therefore he did 1/20 of the work in a day.
Therefore.
[1/15 + 1/20]4 = [4/60 + 3/60]4.
[7/60]4 = 7/15 of the work done.
The total work left = 1 - 7/15 = 15 - 7/ 15 = 8/15.
Swamy akunoori said:
1 decade ago
Good explanation anshu.
Esha said:
1 decade ago
How did 7/20 come?
Rashmi said:
1 decade ago
How did you get 7/60 please answer in simple method and tell how got 7.
Satish said:
1 decade ago
1/15+1/20= 7/60 How ? Please explain me clearly.
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