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 :

1
4

1
10

7
15

8
15

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 30 of 35.

Karthik said:   8 years ago
How comes 300 please explain?

Prabhu said:   8 years ago
Can anyone solve this?

Problem: 'A' can do a piece of in 6days, 'B' in 9days and 'C' in 12 days. In how many days will all of the together finish the work?

Dhananjay Moundekar said:   8 years ago
@Prabhu.

6d/w <= A---->6d
4d/w <= B---->9d
3d/w <= C----->12d

Total Work is LCM of A,B,C =36W

They All do toghether means,
A+B+C=>6+4+3=13d/w
Therefore, A + B + C = 36w/13d/w=2*10/13.

Sneha said:   8 years ago
Therefore, A + B + C = 36w/13d/w=2*10/13. How is it? please explain.

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.

Pooja said:   8 years ago
Why we subtract 7/15 by 1?

Komal said:   7 years ago
Can you explain how 7/60 came?

Ashik said:   7 years ago
If we calculate A and B 's work together 1/15+1/20 then it will came?

Anu said:   7 years ago
How come 7/60?

Miru said:   7 years ago
1-{4(1/15+1/20)}
=1-{4*7/60}
=1-1/15
8/15 is the answer (d).


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