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 6 of 7.
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 :-(
Kiran said:
1 decade ago
B=2A
C=3A
A+B+C=2days
A+2A+3A=2days
so,6A=2days
A only takes (6*2)=12 days
B=2A,so B only takes (12/2)=6days
C=3A
A+B+C=2days
A+2A+3A=2days
so,6A=2days
A only takes (6*2)=12 days
B=2A,so B only takes (12/2)=6days
Md Ali Umar said:
1 decade ago
Hi Mini you are making equ. 2A=B & 3A=C, but so many people a making equ. A=2B & A=3C .
Which one s correct, but both one is getting same answer. I'm confussing in this prob. Pls any one describe it ?
Which one s correct, but both one is getting same answer. I'm confussing in this prob. Pls any one describe it ?
Divya said:
1 decade ago
A=2B=3C
A+B+C=2 ----(EQ.1)
WRITING a and c in terms of b,
A=2B, C=2B/3
IN EQ.1,
2B+B+2B/3=2
3B+2B/3=2
(9B+2B)/3=2
9B+2B=2*3
11B=6
B=6/11
that means, out of 11 days, b alone completes 6 days of work.
A+B+C=2 ----(EQ.1)
WRITING a and c in terms of b,
A=2B, C=2B/3
IN EQ.1,
2B+B+2B/3=2
3B+2B/3=2
(9B+2B)/3=2
9B+2B=2*3
11B=6
B=6/11
that means, out of 11 days, b alone completes 6 days of work.
Mini said:
1 decade ago
A takes twice much time them B i.e. 2A=B...(i)
A takes thrice much time thn C i.e. 3A=C...(ii)
It is given dat workin together they can finish in 2 days
so A+B+C=1/2
Now put B=2A AND C=3A in this equ...
A+B+C=1/2
A+2A+3A=1/2
6A=1/2
A=1/2*6=1/12
Now put the value of A in equ.(i)
.i.e B=2A
=2*1/12
=1/6
Therefore B takes 6 days to complete the work.
A takes thrice much time thn C i.e. 3A=C...(ii)
It is given dat workin together they can finish in 2 days
so A+B+C=1/2
Now put B=2A AND C=3A in this equ...
A+B+C=1/2
A+2A+3A=1/2
6A=1/2
A=1/2*6=1/12
Now put the value of A in equ.(i)
.i.e B=2A
=2*1/12
=1/6
Therefore B takes 6 days to complete the work.
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:
1 decade 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:
1 decade 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)
Lordy said:
1 decade ago
once c the question pls it is mentioned a is twice of b OR thrice of c then how can we divide x,x/2,x/3. if it is mentioned as and then we can decide right?
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