Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 3)
3.
A, B and C can do a piece of work in 20, 30 and 60 days respectively. In how many days can A do the work if he is assisted by B and C on every third day?
Answer: Option
Explanation:
| A's 2 day's work = |  |
1 | x 2 |  |
= | 1 | . |
| 20 | 10 |
| (A + B + C)'s 1 day's work = | |
1 | + | 1 | + | 1 | |
= | 6 | = | 1 | . |
| 20 | 30 | 60 | 60 | 10 |
| Work done in 3 days = | |
1 | + | 1 | |
= | 1 | . |
| 10 | 10 | 5 |
| Now, | 1 | work is done in 3 days. |
| 5 |
Whole work will be done in (3 x 5) = 15 days.
Discussion:
357 comments Page 36 of 36.
Kanishk said:
5 years ago
@Keerthi.
We are not directly multiplying.
We just use the unitary method. Here the total work done is 1. In fact, in all these sums total work is 1.
Now,
Since 1/5th of the work is done in 3 days,
Therefore, 1 of the work( whole work) is done in 3*5 days.
Hope you understand.
We are not directly multiplying.
We just use the unitary method. Here the total work done is 1. In fact, in all these sums total work is 1.
Now,
Since 1/5th of the work is done in 3 days,
Therefore, 1 of the work( whole work) is done in 3*5 days.
Hope you understand.
Pooja Pawatekar said:
5 years ago
How can you take A's 2 days work? Can anyone explain this pls?
Avinash Singh said:
5 years ago
Here's an easy one:
Let's assume that the total work is done in x days.
Then x/3 days, A will require B and C's help and 2x/3 days A will be working alone.
So the equation becomes:
x/3(1/20) + 2x/3(1/20 + 1/30 + 1/60) = 1 [1 because 1 unit of work is done in x days].
Solve it and you'll get x = 15. Thanks!
Let's assume that the total work is done in x days.
Then x/3 days, A will require B and C's help and 2x/3 days A will be working alone.
So the equation becomes:
x/3(1/20) + 2x/3(1/20 + 1/30 + 1/60) = 1 [1 because 1 unit of work is done in x days].
Solve it and you'll get x = 15. Thanks!
Yoezer said:
5 years ago
3 days 1/5.
6 days 2/5.
9 days 3/5.
12 days 4/5.
15 days 5/5( work completed).
6 days 2/5.
9 days 3/5.
12 days 4/5.
15 days 5/5( work completed).
Abdul moeed said:
5 years ago
Use unity rule at the last step,
1/5 work is done in = 3 days.
1 work (whole work) is done in = 3/1/5 = 3*5= 15 days.
1/5 work is done in = 3 days.
1 work (whole work) is done in = 3/1/5 = 3*5= 15 days.
Disha said:
4 years ago
Every 3 days 1/5 work is done. Then in how many days 1 whole work is done.
Mathematically = 1/5:3::1:x.
3*1/ (1/5) = 3÷1/5= 3*5/1= 3*5= 15.
Mathematically = 1/5:3::1:x.
3*1/ (1/5) = 3÷1/5= 3*5/1= 3*5= 15.
Madhu said:
19 hours ago
Yes, I think 20 is the correct answer.
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