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 2 of 7.
Raj said:
9 years ago
2A = B.......eqn1.
3A = C.......eqn2.
A + B + C = 2days
A + 2A + C = 2days (from the eqn1),
A + 2A + 3A = 2days(from the run2),
6A = 2days ,
A = 2/6,
A = 1/3 days.
i.e A takes 3days to work.
We have B=2A.
B=2(3),
B=6.
That's B takes 6 days to complete.
3A = C.......eqn2.
A + B + C = 2days
A + 2A + C = 2days (from the eqn1),
A + 2A + 3A = 2days(from the run2),
6A = 2days ,
A = 2/6,
A = 1/3 days.
i.e A takes 3days to work.
We have B=2A.
B=2(3),
B=6.
That's B takes 6 days to complete.
(1)
Manish said:
8 years ago
One day work of a,b&c=1/2
let a's one-day work=x , then b's one day work 2x & c work 3x
x+2x+3x=1/2
6x=1/2
x=1/12
b's one day work=2*1/12
=1/6
Therefore total work in 6 days.
let a's one-day work=x , then b's one day work 2x & c work 3x
x+2x+3x=1/2
6x=1/2
x=1/12
b's one day work=2*1/12
=1/6
Therefore total work in 6 days.
(1)
Aadhi said:
7 years ago
@Ajay.
How to find efficiency ratio?
How to find efficiency ratio?
(1)
Abhishek said:
5 years ago
Let's assume.
C takes 4 days to do X work.
B takes 6 days for the same X work.
A takes 12 days for the same X work.
so, efficiency
A = 1/12.
B = 1/6.
c = 1/4.
So, as they all together takes 2 days to work,
x/(1/12)+(1/6)+(1/4) = 2
From that, we got X ( total work ) = 1
So time taken alone by;
B = 1/(1/) = 6 days.
C takes 4 days to do X work.
B takes 6 days for the same X work.
A takes 12 days for the same X work.
so, efficiency
A = 1/12.
B = 1/6.
c = 1/4.
So, as they all together takes 2 days to work,
x/(1/12)+(1/6)+(1/4) = 2
From that, we got X ( total work ) = 1
So time taken alone by;
B = 1/(1/) = 6 days.
(1)
G JOGI RAO said:
1 decade ago
Hi @Kiran.
If 6A = 2 then A = 3.
But you said it A = 12 give proper explanation?
If 6A = 2 then A = 3.
But you said it A = 12 give proper explanation?
Vidivelli said:
1 decade ago
Let us consider the time taken by B is 2x.
So the time taken by A is "twice of B" then A=4x.
Similarly if time taken by B is x/2, the time taken by A is (2*x/2) = x; the time taken by C is x/3.
So the time taken by A is thrice of C (3* x/3). Hence we get x+x/2+x/3.
Since we consider work for one day we take inverse 1/x+2/x+3/x = 1/2.
So the time taken by A is "twice of B" then A=4x.
Similarly if time taken by B is x/2, the time taken by A is (2*x/2) = x; the time taken by C is x/3.
So the time taken by A is thrice of C (3* x/3). Hence we get x+x/2+x/3.
Since we consider work for one day we take inverse 1/x+2/x+3/x = 1/2.
Naseem Ahmad Saifi said:
10 years ago
As per given:
2A = B => A = B/2......(1).
3A = C......(2).
=> 3*B/2 = C......(2) (from 1st A = B/2).
(A+B+C)'s do the work in 2 days.
So (A+B+C)'s 1 day work is = 1/2.
Put the value of A and C from 1st and 2nd.
= (B/2+B+3*B/2) 's 1 day work = 1/2.
=> 6B/2, 1 day work = 1/2.
=> B's 1 day work = 1/2*2/6 = 1/6.
So B complete work in 6 days.
2A = B => A = B/2......(1).
3A = C......(2).
=> 3*B/2 = C......(2) (from 1st A = B/2).
(A+B+C)'s do the work in 2 days.
So (A+B+C)'s 1 day work is = 1/2.
Put the value of A and C from 1st and 2nd.
= (B/2+B+3*B/2) 's 1 day work = 1/2.
=> 6B/2, 1 day work = 1/2.
=> B's 1 day work = 1/2*2/6 = 1/6.
So B complete work in 6 days.
Punitsw said:
10 years ago
In simple words:
A:B:C = 1:2:3 (Total 6 equivalent to A).
Now A, B and C together complete work in 2 days (i.e in 12 man days of A). So if A, B or C do the work alone, the required days would be:
A = 12 days.
B = 6 days.
C = 4 days.
A:B:C = 1:2:3 (Total 6 equivalent to A).
Now A, B and C together complete work in 2 days (i.e in 12 man days of A). So if A, B or C do the work alone, the required days would be:
A = 12 days.
B = 6 days.
C = 4 days.
MONA said:
10 years ago
In simple way:
A =2B , A = 3C,So ratio will be = A : B : C = 1 : 2 : 3.
A = 1 unit/day
B = 2unit/day
C = 3unit/day
A + B + C = 6unit/day.
We don't know the total work in units.
So,
A + B + C = 2 Days
TOTAL WORK/DAYS = 6.
TOTAL WORK = 6 * 2 = 12 UNITS.
So,B = 12/2 = 6 Days.
A =2B , A = 3C,So ratio will be = A : B : C = 1 : 2 : 3.
A = 1 unit/day
B = 2unit/day
C = 3unit/day
A + B + C = 6unit/day.
We don't know the total work in units.
So,
A + B + C = 2 Days
TOTAL WORK/DAYS = 6.
TOTAL WORK = 6 * 2 = 12 UNITS.
So,B = 12/2 = 6 Days.
Vandana said:
9 years ago
One query, please answer this question:
A, B and C together can finish a piece of work in 12 days, A and C together work twice as much as B, A and B together work thrice as much as C. In what time could each do it separately?
A, B and C together can finish a piece of work in 12 days, A and C together work twice as much as B, A and B together work thrice as much as C. In what time could each do it separately?
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