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 6 of 35.
SkiGi said:
4 years ago
Why 7/60? I don't understand, please someone explain.
Jigme wangchuk said:
4 years ago
Simple method.
A = 15 days,
B = 20 days,
No days of work together (A+B) = 4 days,
Fraction of work = 4* sum/product.
= 4*(15+20/15*20) =140/300 simplify = 7/15.
Now, remaining fraction of work = 1-7/15
= 8/15.
A = 15 days,
B = 20 days,
No days of work together (A+B) = 4 days,
Fraction of work = 4* sum/product.
= 4*(15+20/15*20) =140/300 simplify = 7/15.
Now, remaining fraction of work = 1-7/15
= 8/15.
Ashutosh Sharma said:
4 years ago
A takes 15 days & B takes 20 days.
L.C.M. of 15 and 20 is 60 ( Total work)
Then
A works in a day 60÷15 = 4 &,
B works in a day 60÷20 = 3.
When both works together;
A+B works in a day (4+3) = 7.
They works for 4 days then 7*4 = 28,
Remaining work is 60 - 28 = 32,
The fraction of left work is 32/60 = 8/15.
L.C.M. of 15 and 20 is 60 ( Total work)
Then
A works in a day 60÷15 = 4 &,
B works in a day 60÷20 = 3.
When both works together;
A+B works in a day (4+3) = 7.
They works for 4 days then 7*4 = 28,
Remaining work is 60 - 28 = 32,
The fraction of left work is 32/60 = 8/15.
Joel said:
4 years ago
Lets take total work is = 1.
In 15 days A will complete the work;
In one day he comlete 1/15 part of work,
Similarly B comletes 1/20 work in one day.
Hence A and B both completes 1/15 + 1/20 work in one day
1/15+1/20 = 7/60.
A and B's one day work,
thier 4 days work = 4 * (7/60) = 28/60 = >7/15,
Now total work is 1,
They completed 7/15 work in 4 days,
Now remaining work is1-7/15 = 8/15.
In 15 days A will complete the work;
In one day he comlete 1/15 part of work,
Similarly B comletes 1/20 work in one day.
Hence A and B both completes 1/15 + 1/20 work in one day
1/15+1/20 = 7/60.
A and B's one day work,
thier 4 days work = 4 * (7/60) = 28/60 = >7/15,
Now total work is 1,
They completed 7/15 work in 4 days,
Now remaining work is1-7/15 = 8/15.
Palak said:
4 years ago
Thanks all.
(1)
Asha Shetty said:
4 years ago
@Mega math.
I can't understand how t simplify 28/60 by 4 and how it becomes 8/15?
I can't understand how t simplify 28/60 by 4 and how it becomes 8/15?
MEGA MATH said:
4 years ago
1/15 + 1/20 = 7/60,
7/60*4 = 28/60,
If we simplify 28/60 by 4, then it is 8/15.
7/60*4 = 28/60,
If we simplify 28/60 by 4, then it is 8/15.
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.
Lohith said:
5 years ago
How (1/15+1/20 )= 7/60? Explain, please.
Surya said:
5 years ago
(1/15+1/20).
Fractions of 15 and 20 are written as;
3*5 and 2'2 *5. = 60,
and 35 go for 7,
= 7/60.
Fractions of 15 and 20 are written as;
3*5 and 2'2 *5. = 60,
and 35 go for 7,
= 7/60.
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