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:
355 comments Page 15 of 36.
SR Ranees said:
6 years ago
Explination for (1/15 + 1/20) = 7/60,
take LCM of 15 and 20.
LCM will be 60,
= (1*4/15*4) + (1*3/20*3),
= (4+3)/60,
= 7/60.
take LCM of 15 and 20.
LCM will be 60,
= (1*4/15*4) + (1*3/20*3),
= (4+3)/60,
= 7/60.
Vaibhav said:
1 decade ago
Why 1-7/15?
The total no. of work is 1 do 1-7/15.
If there are 2 works then 2-7/15.
If 3 works then 3-7/15.
And so on.
The total no. of work is 1 do 1-7/15.
If there are 2 works then 2-7/15.
If 3 works then 3-7/15.
And so on.
Ashish said:
1 decade ago
@Esha.
It's not 7/20 its 7/60 and that came after addition of
Both work A and B
A+B= 1/15+1/20=20+15/15*20=35/300=7/60.
It's not 7/20 its 7/60 and that came after addition of
Both work A and B
A+B= 1/15+1/20=20+15/15*20=35/300=7/60.
Kali said:
1 decade ago
1/15 = 4/60.
1/20 = 3/60.
Simply add 4+3 = 7.
And copy the denominator 60.
LCD:
15 = 5x3.
20 = 5x4.
LCD = 5x3x4 = 60.
1/20 = 3/60.
Simply add 4+3 = 7.
And copy the denominator 60.
LCD:
15 = 5x3.
20 = 5x4.
LCD = 5x3x4 = 60.
Argan Defar said:
10 years ago
For the Question of @Raju,
(A + B)'s completion days = (A * B/(A + B)),
=> 15 * 20/(20 + 15),
=> 300/35 = 8.6 days.
(A + B)'s completion days = (A * B/(A + B)),
=> 15 * 20/(20 + 15),
=> 300/35 = 8.6 days.
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)
Juhi saxena said:
9 years ago
If both 1 day work is 7 then 4 days work is 28 and remaining is 32 how can I change it into fraction? Please explain.
Rasim shaikh said:
1 decade ago
Hello, friends!
Can anybody tell, how 1-7/15 get a plus? and I can't understand where the 1 come?
Please help me.
Can anybody tell, how 1-7/15 get a plus? and I can't understand where the 1 come?
Please help me.
Mish said:
3 years ago
@All.
Why (A+B)'s 4 days of work is calculated?
Why it's not 3,5,6,7 or any other day?
What is the logic behind it?
Why (A+B)'s 4 days of work is calculated?
Why it's not 3,5,6,7 or any other day?
What is the logic behind it?
(10)
Ghhhhgh said:
1 decade ago
Here it is given that A can do a piece of work in 15 days.
So now we can find the A's 1 day work whicvh is =1/15.
So now we can find the A's 1 day work whicvh is =1/15.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers