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 4 of 7.
Rohini said:
1 decade ago
a=2b or a=3c.
=>b=a/2 , c=a/3.
Let us assume a=x.
Then,
a b c
x x/2 x/3
Therefore., (1/x + 2/x + 3/x) = 1/2.
6/x = 1/2.
x = 12.
B alone = x/2 = 12/2 = 6.
=>b=a/2 , c=a/3.
Let us assume a=x.
Then,
a b c
x x/2 x/3
Therefore., (1/x + 2/x + 3/x) = 1/2.
6/x = 1/2.
x = 12.
B alone = x/2 = 12/2 = 6.
Kaviya said:
1 decade ago
How to comes the 1/x+2/x+3/x?
Wangchuk Drukpa said:
1 decade ago
Let C takes x days to complete the work, then:
A, B, C.
3x, 3/2 x and x.
Their respective 1 day's work.
1/3x, 3/2x, 1/x now this is equal to 1/2 (as A+B+C takes 2 days to complete the work, thus their 1 day's work would be half).
Then we get x=4. Now 3/2 of 4 is 6.
A, B, C.
3x, 3/2 x and x.
Their respective 1 day's work.
1/3x, 3/2x, 1/x now this is equal to 1/2 (as A+B+C takes 2 days to complete the work, thus their 1 day's work would be half).
Then we get x=4. Now 3/2 of 4 is 6.
Khushwinder pal said:
1 decade ago
Another method.
Suppose C = X.
C = 2X then B = 3X, A = 6X.
Then B = 2X = 2*3 = 6 days.
If asked A = 6*3 = 18 days.
Suppose C = X.
C = 2X then B = 3X, A = 6X.
Then B = 2X = 2*3 = 6 days.
If asked A = 6*3 = 18 days.
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.
G JOGI RAO said:
10 years 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?
Dipika said:
10 years ago
If C takes x days to complete a work A will take 3x days.
If B takes y days to complete a work A will take 2y days.
But 3x = 2y, so x = 2/3y.
As per ques, 1/2y+y+2/3y = 1/2.
Therefore y = 6.
B takes 6 days to complete the work.
If B takes y days to complete a work A will take 2y days.
But 3x = 2y, so x = 2/3y.
As per ques, 1/2y+y+2/3y = 1/2.
Therefore y = 6.
B takes 6 days to complete the work.
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:
9 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.
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