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:
355 comments Page 32 of 36.
SRI HARSHA.P said:
1 decade ago
The way said by swetha is very long process.
that wastes time in the exam hall.
thats not the good way to do the problem.
always prepare for ashort method.
Short method takes time for the first time by practice it gives u TIME MANAGEMENT. So better to practice SM.
that wastes time in the exam hall.
thats not the good way to do the problem.
always prepare for ashort method.
Short method takes time for the first time by practice it gives u TIME MANAGEMENT. So better to practice SM.
Fouzia said:
1 decade ago
Fouzia.
How that 7 came I can't got it?
How that 7 came I can't got it?
Neha garg said:
1 decade ago
Let total work is 1
1/15+1/20=x/4
7/60*4=x
that means x=7/15
1-7/15=8/15
1/15+1/20=x/4
7/60*4=x
that means x=7/15
1-7/15=8/15
Akanksha said:
2 decades ago
(1/50+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300
= 7/60.
How did 300 came?
= 35/300
= 7/60.
How did 300 came?
Kamal said:
2 decades ago
I didn't undestand last step.
Gowtham said:
2 decades ago
How came remaining days?
Hashir Quraishi said:
2 decades ago
Swetha you rocked.
Sangeetha said:
2 decades ago
Yes swetha your are right. Its very simple and easy method. Thank you.
Pradeepshne said:
2 decades ago
Wow really superb.
Swetha said:
2 decades ago
We can solve this problem by another way also..let us see..
A can do a work in 15 days
B can do a work in 20 days
Take LCM for 15 & 20 i.e Total work = 60
Then,
A's capacity = 60/15 = 4
B's capacity = 60/20 = 3
They work together for 4 days,
Then, A's capacity + B's capacity = 4 + 3 =7
AB's one day capacity = 7
since they work for 4 days, they have done 4x7 =28 work
Work left = Total work - work done by AB
= 60 - 28 = 32
Remaining work / total work = 32 / 60 = 8 / 15
This method will take less time to compute guys...please try it.
A can do a work in 15 days
B can do a work in 20 days
Take LCM for 15 & 20 i.e Total work = 60
Then,
A's capacity = 60/15 = 4
B's capacity = 60/20 = 3
They work together for 4 days,
Then, A's capacity + B's capacity = 4 + 3 =7
AB's one day capacity = 7
since they work for 4 days, they have done 4x7 =28 work
Work left = Total work - work done by AB
= 60 - 28 = 32
Remaining work / total work = 32 / 60 = 8 / 15
This method will take less time to compute guys...please try it.
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