Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 21)
21.
A takes twice as much time as B or thrice as much time as C to finish a piece of work. Working together, they can finish the work in 2 days. B can do the work alone in:
Answer: Option
Explanation:
| Suppose A, B and C take x, | x | and | x | days respectively to finish the work. |
| 2 | 3 |
| Then, |  |
1 | + | 2 | + | 3 |  |
= | 1 |
| x | x | x | 2 |
 |
6 | = | 1 |
| x | 2 |
x = 12.
So, B takes (12/2) = 6 days to finish the work.
Discussion:
68 comments Page 5 of 7.
Manasa said:
1 decade ago
@nayana
GIVEN:
A=2B,A=3C
solution:
consider A can do work in X days
X=2B...B=X/2;X=2C...C=X/3;
B can complete work in X/2days,B's 1 day work is 2/X
C can complete work in X/3days,C's 1 day work is 3/X
A's 1 day work is 1/X.
(A+B+C) 1 days work is[(1/X)+(2/X)+(3/X)]=1/2
6/X=1/2
X=12
therefore b can do work in ;B=X/2=12/2=6 days
GIVEN:
A=2B,A=3C
solution:
consider A can do work in X days
X=2B...B=X/2;X=2C...C=X/3;
B can complete work in X/2days,B's 1 day work is 2/X
C can complete work in X/3days,C's 1 day work is 3/X
A's 1 day work is 1/X.
(A+B+C) 1 days work is[(1/X)+(2/X)+(3/X)]=1/2
6/X=1/2
X=12
therefore b can do work in ;B=X/2=12/2=6 days
Nayana said:
1 decade ago
Hi,
Can any one exaplain why they have taken x,x/2,x/3, because in the question they have given A takes twice as much as B that means two times more than B but they are dividing it.
Can any one exaplain why they have taken x,x/2,x/3, because in the question they have given A takes twice as much as B that means two times more than B but they are dividing it.
Student said:
2 decades ago
Hi thameem, hw can we write a+b=1/2? since three members are working is it not a+b+c=1/2....
please explain
please explain
Thameem said:
2 decades ago
here is another way of solving
given
a=2b
a=3c
a+b=1/2 (work from days)
use a's value in the equation
2b+b=1/2
then 3b=1/2
b=1/6
then b can done work alone in 6 days(days from work)
given
a=2b
a=3c
a+b=1/2 (work from days)
use a's value in the equation
2b+b=1/2
then 3b=1/2
b=1/6
then b can done work alone in 6 days(days from work)
Aashish said:
1 decade ago
Can anyone please explain me how 1/x comes? Because, I formed the equation as x+x/2+x/3=2 and got the wrong answer :-(
Shridhar said:
2 decades ago
As the ques. says,
time taken by A is twice that of B and thrice that of C,so
this means that
A=2*B=3*C ----(eq.1)
dividing the whole equation by lcm(1,2,3)=6,we get
A/6=B/3=C/2
Now
one third of the workdone of B is finished in 2 days
therefore complete workdone of B will be finished in 3*2=6 days.
time taken by A is twice that of B and thrice that of C,so
this means that
A=2*B=3*C ----(eq.1)
dividing the whole equation by lcm(1,2,3)=6,we get
A/6=B/3=C/2
Now
one third of the workdone of B is finished in 2 days
therefore complete workdone of B will be finished in 3*2=6 days.
Keyan said:
2 decades ago
How to solve it in 1:2:3 basis?
Kumar said:
2 decades ago
How the work equation became as (1/x)+(2/x)+(3/x)=1/2
Ananth said:
2 decades ago
How the total work equation became as (1/x)+(2/x)+(3/x)=1/2
Please explain.
Please explain.
Srihari said:
2 decades ago
Hi Meera,
It is not right method because A+B+C's 1 day work is only 1/2 not 1/6.
It is not right method because A+B+C's 1 day work is only 1/2 not 1/6.
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