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 8 of 35.
Rushikesh said:
6 years ago
@Pooja
(1/15)+(1/20).
[(20+15)/(15*20)],
= 35/300,
= 7/60.
(1/15)+(1/20).
[(20+15)/(15*20)],
= 35/300,
= 7/60.
Divye said:
6 years ago
A can complete work in 15 days.
B can complete work in 20 days.
total work (in units) = L.C.M of 15 and 20 => 60 units.
Unit work of A = Total work (in units)/Number of days A take to complete work => 60/15 = 4.
Unit work of B = Total work (in units)/Number of days B take to complete work => 60/20 = 3.
Work done in 1 day by A and B together = Unit work done by A + Unit work done by B => 4+3 = 7.
Work done by A and B together in 4 days = Work done by A and B together in 1 day * 4 => 7 * 4=28.
Work left = Total unit of work - work done by A and B together in 4 days => 60 - 28 = 32.
B can complete work in 20 days.
total work (in units) = L.C.M of 15 and 20 => 60 units.
Unit work of A = Total work (in units)/Number of days A take to complete work => 60/15 = 4.
Unit work of B = Total work (in units)/Number of days B take to complete work => 60/20 = 3.
Work done in 1 day by A and B together = Unit work done by A + Unit work done by B => 4+3 = 7.
Work done by A and B together in 4 days = Work done by A and B together in 1 day * 4 => 7 * 4=28.
Work left = Total unit of work - work done by A and B together in 4 days => 60 - 28 = 32.
Pooja said:
6 years ago
How 7/60 came? Please explain me to get it.
Vikaah yadav said:
6 years ago
Thank for the explanation @Vikash.
Meenu said:
6 years ago
Thanks for explaining @Swetha.
Manikkam said:
6 years ago
1- (7/5) = 8/5.
Because we consider the whole work as 1 then A and B together complete their job for 4 days is 7/5.
Then in the question, they are asking that the fraction of the remaining work so we subtract those values.
Because we consider the whole work as 1 then A and B together complete their job for 4 days is 7/5.
Then in the question, they are asking that the fraction of the remaining work so we subtract those values.
Raj said:
6 years ago
How 1-(7/15)=8/15? Please explain.
Subho said:
7 years ago
Kindly solve it in ratio method.
Esha said:
7 years ago
We consider work done in 15days=1/15 that means a piece of work done in 15 days. Similarly work done in 20 days = 1/20.
So the question is asked for 4 days which means 1/4. So we consider the remaining work to be done as 1.
So the question is asked for 4 days which means 1/4. So we consider the remaining work to be done as 1.
Sai Kumar reddy said:
7 years ago
The common Multiple for 15 and 20 is 5.
A's one day work =15*5=75 units,
B's one day work =20/5=4 units,
Both working together for 4 days=7*4=28 units.
A's one day work =15*5=75 units,
B's one day work =20/5=4 units,
Both working together for 4 days=7*4=28 units.
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