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 8 of 36.
Rehan said:
1 decade ago
We can consider the avg of the 3 days and calculate for total work only if we know the number of days of their work is a multiple of 3. I mean if they had to work for 14 days, b and c would have assisted them only till day 12. On day 13 and 14 again a would have to work alone.
So how can we take 1/5th of work is done in 3 days?
So how can we take 1/5th of work is done in 3 days?
Shruthi said:
8 years ago
From the explaination, we got to know that in 3 day's 1/5 of the work completed.
If A's one day's work is 1/20 then he can complete in 20 days. Same way we should find out 1 day work for the above problem.
i.e., If 3 day's work=1/5.
then one day work=(1/5)/3 =>1/15,
=>so 1 day work=1/15 then he can complete in 15 days.
If A's one day's work is 1/20 then he can complete in 20 days. Same way we should find out 1 day work for the above problem.
i.e., If 3 day's work=1/5.
then one day work=(1/5)/3 =>1/15,
=>so 1 day work=1/15 then he can complete in 15 days.
Baskar said:
1 decade ago
@chitra
assisted by B and C on every third day
it means A's 2 days + (B&C)'s 1 day
from d 1st explanation u got
Work done in 3 days=(1/10 + 1/10)=1/5
dat is in 3 days=1/5 works
in ques dey ask "In how many days can A do the work"
now cross multiply..
(5*3) days=1 work..
1 work = 15 days...
now u got it ah?
assisted by B and C on every third day
it means A's 2 days + (B&C)'s 1 day
from d 1st explanation u got
Work done in 3 days=(1/10 + 1/10)=1/5
dat is in 3 days=1/5 works
in ques dey ask "In how many days can A do the work"
now cross multiply..
(5*3) days=1 work..
1 work = 15 days...
now u got it ah?
Prem Prasidda said:
3 years ago
A = 1/20.
B = 1/30.
C = 1/60.
Now, 1/20+1/30+1/60=5/60 = 1/12.
Here, 1 days efficiency of A is 3, B is 2 and C is 1.
Now,
A can do the work in first day= 3,
" in the second day=3+3=6,
" in third day = 6+6=12,
So, in three days, A completed the work 12.
Now,
12 work = 3 days.
60 work = 3/12*60= 15 days.
B = 1/30.
C = 1/60.
Now, 1/20+1/30+1/60=5/60 = 1/12.
Here, 1 days efficiency of A is 3, B is 2 and C is 1.
Now,
A can do the work in first day= 3,
" in the second day=3+3=6,
" in third day = 6+6=12,
So, in three days, A completed the work 12.
Now,
12 work = 3 days.
60 work = 3/12*60= 15 days.
(102)
Shambhawi said:
7 years ago
I have a very simple solution.
Here it is ->
Let the total number of days in which the work is finished is x.
A will work for x days, B and C will work for x/3 days.
Thus, (A's x days of work) + (B's x/3 days of work) + (C's x/3 days of work) = 1.
Thus -> x/20 + x/(3*30) + x/(3*60) = 1,
Thus-> x = 15.
Here it is ->
Let the total number of days in which the work is finished is x.
A will work for x days, B and C will work for x/3 days.
Thus, (A's x days of work) + (B's x/3 days of work) + (C's x/3 days of work) = 1.
Thus -> x/20 + x/(3*30) + x/(3*60) = 1,
Thus-> x = 15.
Imraz said:
1 decade ago
Here 15 days is required for the completion of the work by A, B, C. But in question it is asked 'in how many days can A do the work' - which means the number of days A worked. So to get this we need to divide the 15 by 3 and get '5' as answer.
Can anyone please make me clear if my interpretation is incorrect ?
Can anyone please make me clear if my interpretation is incorrect ?
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!
Azhar Khan said:
4 years ago
Easy way to answer is:
LCM of 20 30 60 = 60.
A = 20 * 3 = 60,
B = 30 * 2 = 60,
C = 60 * 1 = 60,.
A + B + C = 3 + 2 + 1 = 6 ( together)
A's 2 days work = 2 * 3 = 6.
Total work done by them = 6 + 6 = 12 unit
Total work is 60 unit.
So, 60 ÷ 15 = 5 units ( In one day by them )
Then in 3 days,
3*5 = 15 days
LCM of 20 30 60 = 60.
A = 20 * 3 = 60,
B = 30 * 2 = 60,
C = 60 * 1 = 60,.
A + B + C = 3 + 2 + 1 = 6 ( together)
A's 2 days work = 2 * 3 = 6.
Total work done by them = 6 + 6 = 12 unit
Total work is 60 unit.
So, 60 ÷ 15 = 5 units ( In one day by them )
Then in 3 days,
3*5 = 15 days
(29)
Subasish said:
1 decade ago
A's 1 day work = 1/20
B's 1 day work = 1/30
C's 1 day work = 1/60
since on 3rd day A get assistance of B & C
so 3 days work = A's 3 days work + ( B's + C's )1 day work
= 2*(1/20)+ 1/30 + 1/60
= 12/60 = 1/5
1/5 parts is done by 3 days
1 or whole part is done by (5*3)= 15 days
B's 1 day work = 1/30
C's 1 day work = 1/60
since on 3rd day A get assistance of B & C
so 3 days work = A's 3 days work + ( B's + C's )1 day work
= 2*(1/20)+ 1/30 + 1/60
= 12/60 = 1/5
1/5 parts is done by 3 days
1 or whole part is done by (5*3)= 15 days
Ganesh said:
1 decade ago
Guys, as per my understanding,
1st day A complete 1/20th of work.
2nd day A completes 2/20th of work.
3rd day A along with B and C completes (3/20+1/30+1/60) i.e., 1/5th of the work.
Could some one explain how to calculate?
4th day of A's work ?
5th day of A's work?
6th day of A along with B and C ?
1st day A complete 1/20th of work.
2nd day A completes 2/20th of work.
3rd day A along with B and C completes (3/20+1/30+1/60) i.e., 1/5th of the work.
Could some one explain how to calculate?
4th day of A's work ?
5th day of A's work?
6th day of A along with B and C ?
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