Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 16)
16.
X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?
Answer: Option
Explanation:
| Work done by X in 4 days = |  |
1 | x 4 |  |
= | 1 | . |
| 20 | 5 |
| Remaining work = | |
1 - | 1 | |
= | 4 | . |
| 5 | 5 |
| (X + Y)'s 1 day's work = | |
1 | + | 1 | |
= | 8 | = | 2 | . |
| 20 | 12 | 60 | 15 |
| Now, | 2 | work is done by X and Y in 1 day. |
| 15 |
| So, | 4 | work will be done by X and Y in | |
15 | x | 4 | |
= 6 days. |
| 5 | 2 | 5 |
Hence, total time taken = (6 + 4) days = 10 days.
Discussion:
68 comments Page 4 of 7.
Makvana Disha said:
9 years ago
@Sachin,
2/15 = 1 day work.
Then for remaining work 4/5 = ?
i.e. (4/5) * (15/2) = 6 days.
Total days are, 6 + 4 = 10 days.
2/15 = 1 day work.
Then for remaining work 4/5 = ?
i.e. (4/5) * (15/2) = 6 days.
Total days are, 6 + 4 = 10 days.
Nishesh kumar singh said:
4 years ago
@All.
4/5 is the remaining work which is divided by 2/15 which is 1-day work by x and y to find the no. Of days i.e.4/5/2/15.
4/5 is the remaining work which is divided by 2/15 which is 1-day work by x and y to find the no. Of days i.e.4/5/2/15.
(1)
Sudharsan said:
6 years ago
Why we are adding +4 to the sum the 6 is the work completed until the last. X+4 is just a time taken, why anyone explain?
(3)
Aakash said:
1 decade ago
x+4/20+x/12 = 1.
3(x+4)+5(x)/60 = 1.
3x+12+5x = 60.
8x+12 = 60.
8x = 60-12.
8x = 48.
x = 6.
i.e., x+4 = 6+4.
10 days.
3(x+4)+5(x)/60 = 1.
3x+12+5x = 60.
8x+12 = 60.
8x = 60-12.
8x = 48.
x = 6.
i.e., x+4 = 6+4.
10 days.
Ajay said:
8 years ago
x+4/20+x/12 = 1.
3(x+4)+5(x)/60 = 1.
3x+12+5x = 60.
8x+12 = 60.
8x = 60-12.
8x = 48.
x = 6.
i.e., x+4 = 6+4.
10 days.
3(x+4)+5(x)/60 = 1.
3x+12+5x = 60.
8x+12 = 60.
8x = 60-12.
8x = 48.
x = 6.
i.e., x+4 = 6+4.
10 days.
Shro said:
1 decade ago
6+4 =10
Is here 4 takes from the question? " X started the work alone and then after 4 days"
Is here 4 takes from the question? " X started the work alone and then after 4 days"
Anusha said:
1 decade ago
a = b+b (0.3).
(1/23) = 1.3 b.
b = (10/{23*13}).
b = (10/299).
a+b = 1/13.
So 13 days.
(1/23) = 1.3 b.
b = (10/{23*13}).
b = (10/299).
a+b = 1/13.
So 13 days.
Sachin said:
9 years ago
Please help me to understand this, why we took 15/2 instead of 2/15?
Thank in advance.
Thank in advance.
Nik said:
9 years ago
But here it asked like "how long did they work", why should we consider A's work here?
Nikhil said:
2 decades ago
2/15 work done by x and y in one day.
Then how you are taking reciprocal 15/2*4/5.
Then how you are taking reciprocal 15/2*4/5.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers