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:
355 comments Page 18 of 36.
Vamshi said:
1 decade ago
@Deepa.
(1/15+1/20) L.C.M of 15, 20 is 60.
So 1/15*60 = 4.
And 1/20*60 = 3.
4+3/60 = 7/60.
(1/15+1/20) L.C.M of 15, 20 is 60.
So 1/15*60 = 4.
And 1/20*60 = 3.
4+3/60 = 7/60.
Sassy said:
1 decade ago
I'm not getting it at all can someone explain it why 70/60 in the easiest explanation please.
Vinay gudipati said:
8 years ago
Very simple,
15+20=35,
15*20=300,
35/300=7/60,
work is 1 so=1-7/15.
=15-7/15,
Ans is = 8/15.
15+20=35,
15*20=300,
35/300=7/60,
work is 1 so=1-7/15.
=15-7/15,
Ans is = 8/15.
Dinesh said:
1 decade ago
This problem ok I can understand but some other problems I can't understand my dear friends.
Sak said:
2 decades ago
1/15 * 4/4 = 4/60 ok.
1/20 * 3/3 = 3/60 ok.
How do we get 4/4 and 3/3 ? Please explain.
1/20 * 3/3 = 3/60 ok.
How do we get 4/4 and 3/3 ? Please explain.
DEEPAK said:
1 decade ago
A = 20, B = 15.
TOTAL WORK FOR ONE DAYS = 7/60.
4 DAYS = 7/15.
Remaining work = 8/15.
TOTAL WORK FOR ONE DAYS = 7/60.
4 DAYS = 7/15.
Remaining work = 8/15.
Aravind said:
1 decade ago
Why calculate the remaining work (1-7/15) ? The question ask to find the fraction left.
Sri said:
10 years ago
Please give the short trick 'with efficiency' then the sum will be solved very quickly.
Rinkesh said:
1 decade ago
Very simple,
15+20=35
15*20=300
35/300=7/60
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
15+20=35
15*20=300
35/300=7/60
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
Rahul said:
1 decade ago
Can you just guide me to know that how can we calculate the LCM of says 8, 24, 60/7.
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