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.
Well wisher said:
1 decade ago
@Poorni:
Why 1-(7/15)?
We consider the total work as 1.
The amount of (work done) is 7/15.
Subtract the total work by the work done we will get the amount of work to be done
That is why we use 1-(7/15).
Hope this help you.
Why 1-(7/15)?
We consider the total work as 1.
The amount of (work done) is 7/15.
Subtract the total work by the work done we will get the amount of work to be done
That is why we use 1-(7/15).
Hope this help you.
Dhananjay Moundekar said:
8 years ago
@Prabhu.
6d/w <= A---->6d
4d/w <= B---->9d
3d/w <= C----->12d
Total Work is LCM of A,B,C =36W
They All do toghether means,
A+B+C=>6+4+3=13d/w
Therefore, A + B + C = 36w/13d/w=2*10/13.
6d/w <= A---->6d
4d/w <= B---->9d
3d/w <= C----->12d
Total Work is LCM of A,B,C =36W
They All do toghether means,
A+B+C=>6+4+3=13d/w
Therefore, A + B + C = 36w/13d/w=2*10/13.
Durga prasad said:
2 years ago
Lcm of 15 and 30 = 60 units.
A's per day work = 60/15 = 4units.
B's per day work = 60/20 = 3units.
A+B's per day work = 4 + 3 = 7units.
A and B together do the work in 4 days.
= 4 * 7 = 28units.
Remaining work = 32/60 = 8/15.
A's per day work = 60/15 = 4units.
B's per day work = 60/20 = 3units.
A+B's per day work = 4 + 3 = 7units.
A and B together do the work in 4 days.
= 4 * 7 = 28units.
Remaining work = 32/60 = 8/15.
(196)
UMAKANT CHAUDHARY said:
1 month ago
To solve this type of question,if days are given and if we have to find together work finishing days then,
= (15+20)/15 * 20,
= 35/300,
= 7/60.
Now, in 4 days they can do 4 * 7/60,
= 7/15.
So, Remaining work = 1-(7/15).
= 8/15.
= (15+20)/15 * 20,
= 35/300,
= 7/60.
Now, in 4 days they can do 4 * 7/60,
= 7/15.
So, Remaining work = 1-(7/15).
= 8/15.
(12)
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.
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.
Sundar said:
1 decade ago
@Vijay Kumar
1/15 + 1/20 = ?
1/15 * 4/4 = 4/60 ok.
1/20 * 3/3 = 3/60 ok.
Now,
4/60 + 3/60 = (4+3)/60 = 7/60. Thats all.
I don't know how to explain more simpler than this. Hope you can understand this. Have a nice day!
1/15 + 1/20 = ?
1/15 * 4/4 = 4/60 ok.
1/20 * 3/3 = 3/60 ok.
Now,
4/60 + 3/60 = (4+3)/60 = 7/60. Thats all.
I don't know how to explain more simpler than this. Hope you can understand this. Have a nice day!
Sahil said:
2 years ago
4( 1/15 + 1/20 ) = work done by both of them together
Work Done + Work left =1 =>because the work is 100% completed
4( 1/15 + 1/20 ) + work left = 1;
work left = 1 - (28/ 60);
Then, work left = 8/15;
Work Done + Work left =1 =>because the work is 100% completed
4( 1/15 + 1/20 ) + work left = 1;
work left = 1 - (28/ 60);
Then, work left = 8/15;
(66)
Shiyamala said:
1 decade ago
A=1/15;B=1/20
[A+B]=[1/15+1/20] {1/15*20/20=20/300; 1/20*15/15=15/300}
=20+15/15*20 {cross multiplication}
=35/300 {20+15=35;15*20=300}
=7/60
7/60*4=28/60 {4*7=28}
=7/15
[A+B]=[1/15+1/20] {1/15*20/20=20/300; 1/20*15/15=15/300}
=20+15/15*20 {cross multiplication}
=35/300 {20+15=35;15*20=300}
=7/60
7/60*4=28/60 {4*7=28}
=7/15
Kundan said:
5 years ago
A one day work = 1/15.
B one day work = 1/20.
One day work of both = 1/15 + 1/20 = 7/60.
4days work of both = 7/60 * 4 = 7/15 is the total work of 4days.
So, remaining days work = 1 - 7/15 = 8/15.
Hence, 8/15 answer.
B one day work = 1/20.
One day work of both = 1/15 + 1/20 = 7/60.
4days work of both = 7/60 * 4 = 7/15 is the total work of 4days.
So, remaining days work = 1 - 7/15 = 8/15.
Hence, 8/15 answer.
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