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 3 of 36.
Poojitha said:
4 years ago
@Dhanam.
Because on third day they are doing combined work it means that for 1st 2 days they have worked alone here in question. About A has asked so he is doing only A.
Because on third day they are doing combined work it means that for 1st 2 days they have worked alone here in question. About A has asked so he is doing only A.
(3)
Sairam said:
4 years ago
@Kiran.
You didn't account for A's third day of work.
A does 6 units of work in two days and another 3 units on the third day. So in total, A has done 9 units of work in 3 days.
You didn't account for A's third day of work.
A does 6 units of work in two days and another 3 units on the third day. So in total, A has done 9 units of work in 3 days.
(1)
Kiran said:
4 years ago
Hi, can anyone tell me what's wrong here?
Given,
A=20days.
B=30days.
C=60days.
I took as 60units of work by taking LCM of A, B, C.
A's one day work=3 units/day.
B's one day work=2 units/day.
A's two days work = 6 units.
B's one day work= 2 units.
C's one day work= 1 unit.
A+B+C's 3 days work = 9 units.
So, I can take A+B+C's one day work = 3 units =>9/3=3 units/day.
So, to complete 60 units of work they will take 20days =>20*3=60 units.
So, I am saying that answer is "20 days".
Correct me if I'm wrong.
Given,
A=20days.
B=30days.
C=60days.
I took as 60units of work by taking LCM of A, B, C.
A's one day work=3 units/day.
B's one day work=2 units/day.
A's two days work = 6 units.
B's one day work= 2 units.
C's one day work= 1 unit.
A+B+C's 3 days work = 9 units.
So, I can take A+B+C's one day work = 3 units =>9/3=3 units/day.
So, to complete 60 units of work they will take 20days =>20*3=60 units.
So, I am saying that answer is "20 days".
Correct me if I'm wrong.
(1)
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.
Amit bhau said:
4 years ago
3 days ---> work 1/5
x days ---> to get total work =1
Cross multiplication, then we get x = 15.
x days ---> to get total work =1
Cross multiplication, then we get x = 15.
(1)
T.S said:
5 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:
5 years ago
How we got only A done 3 days of work? Please explain it.
(1)
Usman said:
5 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:
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.
Arun said:
5 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)
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