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 3 of 35.
Dinesh kumar said:
2 years ago
A = 1/15
B = 1/20
(A+B) = 1/15+1/20 = 7/15
The remaining work = 1-7/15 = 8/15.
B = 1/20
(A+B) = 1/15+1/20 = 7/15
The remaining work = 1-7/15 = 8/15.
(26)
NADIPUDI SIRISHA said:
2 years ago
Thank you for explaining the answer @Giri.
(26)
Anonym said:
1 year ago
A, completes the work in 15 days so, the work done by A in 1 day = 1/15.
Similarly, B completes the work in 20 days therefore work done by B in 1 day = 1/20.
A and b work together = 1/15+1/20 i.e. => 14/120 => 7/60.
Now, they both worked for 4 days which will be = 4*7/60 => 7/15.
Let's suppose the total work is x and they have already worked for 4 days.
Therefore remaining work is x -7/15 (for more clarity take x-7/15 = 0) => 8/15.
Similarly, B completes the work in 20 days therefore work done by B in 1 day = 1/20.
A and b work together = 1/15+1/20 i.e. => 14/120 => 7/60.
Now, they both worked for 4 days which will be = 4*7/60 => 7/15.
Let's suppose the total work is x and they have already worked for 4 days.
Therefore remaining work is x -7/15 (for more clarity take x-7/15 = 0) => 8/15.
(25)
Nitika said:
1 year ago
The reason why we've subtract from 1:
1 represents the whole work or complete work total work considered as 1(or 100%)
1 represents the whole work or complete work total work considered as 1(or 100%)
(23)
Bha said:
12 months ago
Thanks all for explaining the answer.
(23)
Raghu said:
1 year ago
How 7 comes? Please explain.
(22)
Jeevanantham M said:
2 years ago
@Ayansh.
For this;
(A+B) 's work rate = 1/15 + 1/20 = (4/60 + 3/60) = 7/60.
For this;
(A+B) 's work rate = 1/15 + 1/20 = (4/60 + 3/60) = 7/60.
(21)
Sowmiya said:
1 year ago
How remaing work =1? Please explain to me.
(20)
Radhika said:
3 years ago
@All.
As 1 is the whole work, so when we subtract 7/15 from 1.
Then,
LCM of 1 and 15 will be 15 ( in 1 the denominator will be 1 ).
So, 15-7/15 is 8/15.
As 1 is the whole work, so when we subtract 7/15 from 1.
Then,
LCM of 1 and 15 will be 15 ( in 1 the denominator will be 1 ).
So, 15-7/15 is 8/15.
(18)
RichardAnthony said:
2 years ago
Just take LCM of 15 and 20 you will get total work of 60.
(17)
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