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:
353 comments Page 14 of 36.
Jansi said:
1 decade ago
I understood upto 7/15. I can't understand how they are telling total work 1. From that they were minusing 7/15 can you explain me.
Aravind_appu said:
1 decade ago
A = 1/15.
B = 1/20.
Together TH = A+B.
TH = (1/15+1/20).
TH/4 = (1/15+1/20).
TH = 4((35/15*20)).
TH = 7/15.
= 1-7/15 = 8/15.
B = 1/20.
Together TH = A+B.
TH = (1/15+1/20).
TH/4 = (1/15+1/20).
TH = 4((35/15*20)).
TH = 7/15.
= 1-7/15 = 8/15.
ASHLYMOL SAJU said:
1 decade ago
A B A+B.
15 20 4.
Work = Efficiency/Time.
Work = LCM of A B A+B.
W = 60.
A B A+B = 4 3 15.
Total = 7/15.
Remaining = 8/15.
15 20 4.
Work = Efficiency/Time.
Work = LCM of A B A+B.
W = 60.
A B A+B = 4 3 15.
Total = 7/15.
Remaining = 8/15.
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:
2 decades 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:
2 decades 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.
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