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:
362 comments Page 4 of 37.
T.S said:
6 years ago
@Vijay
We know that the whole work done is 1. here 3 days work is 1/5.
So,
if, 1/5 work=3days.
then, 1 work= ?
Cross multiply we get ?= 3 x 5= 15days.
We know that the whole work done is 1. here 3 days work is 1/5.
So,
if, 1/5 work=3days.
then, 1 work= ?
Cross multiply we get ?= 3 x 5= 15days.
(1)
Vijay said:
6 years ago
How we got only A done 3 days of work? Please explain it.
(1)
Usman said:
6 years ago
Solution:
A do a piece of work in = 1/20 days.
'A' work alone for 2 days, so the work done by A on the second day is = 2/20 = 1/10
On the third day, A is assisted by B&C, then the work done by three of them is = 1/10 + 1/20 + 1/30 = 3/20.
Total work done by A in 3 days is = 1/20 + 3/20 = 1/5.
As we have to find number of days, so,
1/5 part of work done by A is in = 3 days.
1 part of the work done by A is in = 3x5 = 15 days.
In 15 days, A can do the work if he is assisted by B& C on the third day.
A do a piece of work in = 1/20 days.
'A' work alone for 2 days, so the work done by A on the second day is = 2/20 = 1/10
On the third day, A is assisted by B&C, then the work done by three of them is = 1/10 + 1/20 + 1/30 = 3/20.
Total work done by A in 3 days is = 1/20 + 3/20 = 1/5.
As we have to find number of days, so,
1/5 part of work done by A is in = 3 days.
1 part of the work done by A is in = 3x5 = 15 days.
In 15 days, A can do the work if he is assisted by B& C on the third day.
(4)
Abdul moeed said:
6 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.
Arun said:
6 years ago
Worker - TotalDay - OneDay
A - 20 - 1/20
B - 30 - 1/30
C - 60 - 1/60
1st Day - A.
2nd Day- B.
3rd Day - A, B, C.
They said A lonely can work for 2 day.
2A = 2(1/20) =1/10.
Then in third day A, B, C together;
(A+B+C) = 1/20+1/30+1/60,
= 1/10.
3 Days(not 3rd Day) work is;
=2A + (A+B+C).
= 1/10+1/10.
3Days =1/5 work,
6Days =2/5 work,
9Days =3/5 work,
12Days=4/5 work,
15Days= 5/5 =1 work completed.
A - 20 - 1/20
B - 30 - 1/30
C - 60 - 1/60
1st Day - A.
2nd Day- B.
3rd Day - A, B, C.
They said A lonely can work for 2 day.
2A = 2(1/20) =1/10.
Then in third day A, B, C together;
(A+B+C) = 1/20+1/30+1/60,
= 1/10.
3 Days(not 3rd Day) work is;
=2A + (A+B+C).
= 1/10+1/10.
3Days =1/5 work,
6Days =2/5 work,
9Days =3/5 work,
12Days=4/5 work,
15Days= 5/5 =1 work completed.
(5)
Sunil_ said:
6 years ago
A work in one day = 1/20,
B work in one day = 1/30,
C work in one day = 1/60.
As A work for 2 days and then on third day B and C do work.
Total work done in three days = A 3 days work+B 1-day work+ C one day work,
= 3/20 + 1/30 + 1/60,
= 9/60 + 2/60 + 1/60
= 12/60.
Total work is done in three days =1/5.
3 = 1/5part.
Let x days required to complete work = 1 part.
3/x = 1/5/1.
x = 3 * 5 = 15 days.
B work in one day = 1/30,
C work in one day = 1/60.
As A work for 2 days and then on third day B and C do work.
Total work done in three days = A 3 days work+B 1-day work+ C one day work,
= 3/20 + 1/30 + 1/60,
= 9/60 + 2/60 + 1/60
= 12/60.
Total work is done in three days =1/5.
3 = 1/5part.
Let x days required to complete work = 1 part.
3/x = 1/5/1.
x = 3 * 5 = 15 days.
(1)
Yoezer said:
6 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).
Britney said:
6 years ago
How did we get 6/60? Anyone explain about it.
(1)
Avinash Singh said:
6 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!
Pooja Pawatekar said:
6 years ago
How can you take A's 2 days work? Can anyone explain this pls?
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