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 31 of 36.
Atma kumar vishwakarma said:
8 years ago
Let both making toffee.
The total toffee they made is 60 it LCM of 20 and15.
mins A make 60 toffee in 15 days it mins A make 4 toffee a day,
B makes 60 toffee in 20 days it mins B make 3 toffy a day they work together for day
it mins (3+4)*4=28.
In 4 days they made 28 toffee they need to make 60 toffee.
It mins 28/60=7/15.
The total toffee they made is 60 it LCM of 20 and15.
mins A make 60 toffee in 15 days it mins A make 4 toffee a day,
B makes 60 toffee in 20 days it mins B make 3 toffy a day they work together for day
it mins (3+4)*4=28.
In 4 days they made 28 toffee they need to make 60 toffee.
It mins 28/60=7/15.
Pooja said:
8 years ago
Why we subtract 7/15 by 1?
Komal said:
8 years ago
Can you explain how 7/60 came?
Ashik said:
8 years ago
If we calculate A and B 's work together 1/15+1/20 then it will came?
Anu said:
8 years ago
How come 7/60?
Miru said:
8 years ago
1-{4(1/15+1/20)}
=1-{4*7/60}
=1-1/15
8/15 is the answer (d).
=1-{4*7/60}
=1-1/15
8/15 is the answer (d).
Mogarg said:
8 years ago
@All
Here is the Concept of 1.
If a can do work in 5 days, then,
In one day = 1/5.
In 5 days = 1/5+1/5+1/5+1/5+1/5.
= 5/5 =1.
the concept of 1 means total work, not a day so assume our total work 1.
Here is the Concept of 1.
If a can do work in 5 days, then,
In one day = 1/5.
In 5 days = 1/5+1/5+1/5+1/5+1/5.
= 5/5 =1.
the concept of 1 means total work, not a day so assume our total work 1.
Abhinesh said:
8 years ago
Let,
Do in this way;
Use formula= xy/x+y.
X is 15 and Y 30 if you cross multiply you get an answer.
Do in this way;
Use formula= xy/x+y.
X is 15 and Y 30 if you cross multiply you get an answer.
TRUPTIMAYEE BAHINIPATI said:
8 years ago
Why we subtract 7/15 by 1?
Solution:
Here we consider that the total work is 1.
A&B do a certain work that we don't know so at first we need find the unit of work in 1day
then A+B's working unit per 4 days.
After that we got A&B's total unit of work done ;which is substrated by 1 to got the remaining work.
Solution:
Here we consider that the total work is 1.
A&B do a certain work that we don't know so at first we need find the unit of work in 1day
then A+B's working unit per 4 days.
After that we got A&B's total unit of work done ;which is substrated by 1 to got the remaining work.
Fazeena said:
8 years ago
I can't understand 1-7/15.
So, please explain me again or another way.
So, please explain me again or another way.
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