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.
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.
Jatinder said:
7 years ago
a---12 days .
b ----6 days.
c --- 4 days.
lcm of 12,6,4 = 12.
The work done in one day by
A- 1
B-2
C-3
then total work done by B in 6 days.
6 is the answer.
b ----6 days.
c --- 4 days.
lcm of 12,6,4 = 12.
The work done in one day by
A- 1
B-2
C-3
then total work done by B in 6 days.
6 is the answer.
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?
Rexi said:
6 years ago
Simply, it is solved by;
A=2B ; A=3C.
A/2=B ; A/3=C ---> time,
2/A=B; 3/A=C ---> efficiency,
1/A+2/A+3/A = 1/2 ---> A+B+C=1/2.
A = 12,
B = 6,
C = 4.
A=2B ; A=3C.
A/2=B ; A/3=C ---> time,
2/A=B; 3/A=C ---> efficiency,
1/A+2/A+3/A = 1/2 ---> A+B+C=1/2.
A = 12,
B = 6,
C = 4.
(4)
Mariam said:
1 decade ago
Hai guys, i think mini is correct. from the question we get if B works for 1 hr, A takes 2 hrs to complete the same work i.e.,2A=B
Rakib said:
9 years ago
Let A = 12 days(twice than B& thrice than C),
B = 6 days,
C = 4 days.
Working together: (12 * 1/2) = 6 days.
Am I Right?
B = 6 days,
C = 4 days.
Working together: (12 * 1/2) = 6 days.
Am I Right?
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.
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 :-(
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
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
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