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 12 of 36.
Anjali thakur said:
1 year ago
The answer is 8/15.
Lcm of 15 and 20.
Then it will give you 60.
Now 60/15 = 4, 60/20 = 3.
Together for one day 4 + 3=7.
For 4 days = 4 * 7=28.
60-28 = 32.
32/60 = 8/15.
Lcm of 15 and 20.
Then it will give you 60.
Now 60/15 = 4, 60/20 = 3.
Together for one day 4 + 3=7.
For 4 days = 4 * 7=28.
60-28 = 32.
32/60 = 8/15.
(71)
Anand said:
1 decade ago
Balance work = 8/15.
A = 1/15, B = 1/20.
Total no of days required to complete remaining work.
A = (8/15) / (1/15) = 8 days,
B = (8/15) / (1/20) = 10 2/3 days.
A = 1/15, B = 1/20.
Total no of days required to complete remaining work.
A = (8/15) / (1/15) = 8 days,
B = (8/15) / (1/20) = 10 2/3 days.
Ambika said:
2 months ago
A ---> 15 days.
B ---> 20 days.
LCM --> 60.
A--> efficiency 4.
B--> efficiency 3.
Total 4 days work = 4 * 7 = 28.
Remaining work = 60 - 28 = 32.
32/60 = 8/15.
B ---> 20 days.
LCM --> 60.
A--> efficiency 4.
B--> efficiency 3.
Total 4 days work = 4 * 7 = 28.
Remaining work = 60 - 28 = 32.
32/60 = 8/15.
(29)
Srikanth said:
1 decade ago
In all these problems total work taken as "1" so we have to remove the resulting answer i.e., 7/15 from total work"1" so remaining work is (1-7/15) i.e., 8/15.
PriyA said:
1 decade ago
But still I can't understand the logic behind the subtraction of 1. I have read @Mangesh answer. But why do we assume "one"? They did't mention anything right?
Virat said:
6 years ago
A=15 Days.
B=20 Days.
LCM 60.
A's 1 Day work=4.
B's 1 Day work=3.
Both together 1 Day work= 7/60.
Both together 4 Days work= 28/60.
Rest work= 32/60 = 8/15.
B=20 Days.
LCM 60.
A's 1 Day work=4.
B's 1 Day work=3.
Both together 1 Day work= 7/60.
Both together 4 Days work= 28/60.
Rest work= 32/60 = 8/15.
Malik shahnawaz said:
4 months ago
W(A) = eff * time = 4 * 4 = 16
W(B) = rff * time = 3 * 4 = 12.
Total work in 4 days = 28.
Remaining work = 60 - 28 = 32.
Fraction of work left = 32/60 = 8/15.
W(B) = rff * time = 3 * 4 = 12.
Total work in 4 days = 28.
Remaining work = 60 - 28 = 32.
Fraction of work left = 32/60 = 8/15.
(30)
Meena said:
1 decade ago
Fraction of work done in 4 days = 7/15.
(It means that out of 15 parts, 7 parts has been done. So 8 parts left)
Therefore, the fraction of work left = 8/15.
(It means that out of 15 parts, 7 parts has been done. So 8 parts left)
Therefore, the fraction of work left = 8/15.
Prabhu said:
9 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?
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?
VisHnu RaM said:
4 years ago
Thank you for giving the clear explanation @Swetha.
And 60 will come, No of days LCM
15 days to 15 * 4 = 60.
20 days to 20 * 3 = 60.
So, the LCM is 60.
And 60 will come, No of days LCM
15 days to 15 * 4 = 60.
20 days to 20 * 3 = 60.
So, the LCM is 60.
(13)
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