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 2 of 35.
Vishwanath said:
1 decade ago
7/60 x4 =7/15 please explain me
Well wisher said:
1 decade ago
@Poorni:
Why 1-(7/15)?
We consider the total work as 1.
The amount of (work done) is 7/15.
Subtract the total work by the work done we will get the amount of work to be done
That is why we use 1-(7/15).
Hope this help you.
Why 1-(7/15)?
We consider the total work as 1.
The amount of (work done) is 7/15.
Subtract the total work by the work done we will get the amount of work to be done
That is why we use 1-(7/15).
Hope this help you.
Malli said:
1 decade ago
@Prkash.
Superb explaination.
Superb explaination.
Lottie said:
1 decade ago
I was thinking 1-7/15 will be 6/15. So how did you get 8/15. Thanx.
Analyser said:
1 decade ago
Since work done is 7/15....which is 7 parts out of 15.....
So obviously total work wud be 15/15......which is 1....
Hence we subtract 7/15...from 15/15 or 1..... i.e 1-7/15.
So obviously total work wud be 15/15......which is 1....
Hence we subtract 7/15...from 15/15 or 1..... i.e 1-7/15.
Vijay kumar said:
1 decade ago
Can you explain how 7/60 came ?
Sundar said:
1 decade ago
@Vijay Kumar
1/15 + 1/20 = ?
1/15 * 4/4 = 4/60 ok.
1/20 * 3/3 = 3/60 ok.
Now,
4/60 + 3/60 = (4+3)/60 = 7/60. Thats all.
I don't know how to explain more simpler than this. Hope you can understand this. Have a nice day!
1/15 + 1/20 = ?
1/15 * 4/4 = 4/60 ok.
1/20 * 3/3 = 3/60 ok.
Now,
4/60 + 3/60 = (4+3)/60 = 7/60. Thats all.
I don't know how to explain more simpler than this. Hope you can understand this. Have a nice day!
Sheelu said:
1 decade ago
1/15+1/20=7/60
7/60*4=8/15
7/60*4=8/15
Sagar said:
1 decade ago
@deepa
lcm of 15 and 20 is 60 so we get 7/60
understood
lcm of 15 and 20 is 60 so we get 7/60
understood
Amrinder said:
1 decade ago
4/60 is ok 4 is no of working and 60 is hours in day
cant undestand 3/60
cant undestand 3/60
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