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 14 of 35.
Swetha said:
1 decade ago
@Sri harsha.p
It is not very long process..it is short method only.i explained every steps.,so only it looks like long process.
It is not very long process..it is short method only.i explained every steps.,so only it looks like long process.
Sunny guleria said:
1 decade ago
We have to calculate the remaining work after 4 dayz ,so why we subtract 1 dayz work from 4 day work? plz clear the question.
Shrikant said:
1 decade ago
a/b + c/d.
= a*d/b*d + c*b/b*d.
= ad+cb/b*d.
Maths rule if denominator not equal if equal directly cross multiplication.
= a*d/b*d + c*b/b*d.
= ad+cb/b*d.
Maths rule if denominator not equal if equal directly cross multiplication.
Shiva said:
1 decade ago
@Kiran.
(1/15+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300.
= 7/60.
I think your doubt is clear now.
(1/15+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300.
= 7/60.
I think your doubt is clear now.
Appu said:
1 decade ago
@Deepa
(1/50+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300
= 7/60.
I think your doubt is clear now.
(1/50+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300
= 7/60.
I think your doubt is clear now.
(1)
SR Ranees said:
5 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:
9 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.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers