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 4 of 35.
Sak said:
1 decade ago
1/15 * 4/4 = 4/60 ok.
1/20 * 3/3 = 3/60 ok.
How do we get 4/4 and 3/3 ? Please explain.
1/20 * 3/3 = 3/60 ok.
How do we get 4/4 and 3/3 ? Please explain.
Mani said:
1 decade ago
Still i have confusion. How 7/60 comes?
Honeymayee said:
1 decade ago
Power of a=p1=w/15
Power of b=p2=w/20
Work is same so p1*15=p2*20
p1/p2=4/3
Now I do not know how to proceed. ?
Power of b=p2=w/20
Work is same so p1*15=p2*20
p1/p2=4/3
Now I do not know how to proceed. ?
Ni333 said:
1 decade ago
Thanks analyser.
Urmm said:
1 decade ago
L.C.M. of 15 & 20 are 60
and 60/15=4
and 60/20=3
so 4+3=7 as numerator
and 60 is denominator
OR
1/15+1/20=[(1*20)+(1*15)]/300=(20+15)/300=35/300=7/60
35 devide by 5 and 300 devide by 5
and 60/15=4
and 60/20=3
so 4+3=7 as numerator
and 60 is denominator
OR
1/15+1/20=[(1*20)+(1*15)]/300=(20+15)/300=35/300=7/60
35 devide by 5 and 300 devide by 5
Swetha said:
1 decade 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.
(1)
Pradeepshne said:
1 decade ago
Wow really superb.
Sangeetha said:
1 decade ago
Yes swetha your are right. Its very simple and easy method. Thank you.
Hashir Quraishi said:
1 decade ago
Swetha you rocked.
Gowtham said:
1 decade ago
How came remaining days?
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