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:
351 comments Page 3 of 36.
Sree said:
1 year ago
How 7/60 came? please anyone explain to me?
(33)
Ganesh said:
2 months ago
Here, asking for the remaining work.
So,
A can finish in 15, B can finish it in 20 days, respectively.
So, 15, 20 -> LCM 60.
A = 15 * 4 =60.
So, A'efficiency is 4.
B efficiency = 3.
TOTAL WORK 60.
A + B WORK.
Then efficiency or one day works together is 4 + 3 = 7,
Total 4 days* 7 = 28,
Remaining work is 60 - 28 = 32.
So here asking for the remaining work, only 32/60.
So, finally the remaining work is 8/15.
So,
A can finish in 15, B can finish it in 20 days, respectively.
So, 15, 20 -> LCM 60.
A = 15 * 4 =60.
So, A'efficiency is 4.
B efficiency = 3.
TOTAL WORK 60.
A + B WORK.
Then efficiency or one day works together is 4 + 3 = 7,
Total 4 days* 7 = 28,
Remaining work is 60 - 28 = 32.
So here asking for the remaining work, only 32/60.
So, finally the remaining work is 8/15.
(30)
Zak said:
3 years ago
How come 7/60? Please explain.
(29)
Dinesh kumar said:
3 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:
2 years 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.
(26)
Nitika said:
2 years 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%)
(25)
Bha said:
2 years ago
Thanks all for explaining the answer.
(24)
Raghu said:
2 years ago
How 7 comes? Please explain.
(22)
Jeevanantham M said:
3 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)
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers