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 20 of 35.

Sangeetha said:   1 decade ago
Yes swetha your are right. Its very simple and easy method. Thank you.

Prashant Devada said:   8 years ago
@Akash.

You are great, LCM concept makes easy to understand.

Thanks.

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

Gurdeep said:   1 decade ago
@Jansi.

Both A and B doing the same (one) work, not different work.

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

Lottie said:   1 decade ago
I was thinking 1-7/15 will be 6/15. So how did you get 8/15. Thanx.

Rajesh Chowdary said:   1 decade ago
Explanations are good plz share any simple methods other than these

Shubham mishra said:   8 years ago
@Ankit kain.

In the last step why you take 28/60 instead of 60/28?

Praveen behera said:   8 years ago
Why (1- 7/15) is applied as 8/15?

Can anybody explain it please?

Vinod said:   1 decade ago
Any one can explain me why we using remaining work 1-7/15 please.


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