Aptitude - Pipes and Cistern - Discussion
Discussion Forum : Pipes and Cistern - General Questions (Q.No. 12)
12.
A large tanker can be filled by two pipes A and B in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half?
Answer: Option
Explanation:
| Part filled by (A + B) in 1 minute = |  |
1 | + | 1 |  |
= | 1 | . |
| 60 | 40 | 24 |
Suppose the tank is filled in x minutes.
| Then, | x | |
1 | + | 1 | |
= 1 |
| 2 | 24 | 40 |
 |
x | x | 1 | = 1 |
| 2 | 15 |
x = 30 min.
Discussion:
51 comments Page 1 of 6.
Kumar said:
1 decade ago
Some one explain in more detailed manner.
Ishan said:
1 decade ago
We have to consider half time for both b and (a and b).
So if we consider time =x min then..for half time we have to take x/2 so we get x\2(1/40)wich is for b + x/2(1/24)wich is for both a and b.
So taking common we get x/2(1/40+1/24)=1 which 1 means to full whole tank.
So if we consider time =x min then..for half time we have to take x/2 so we get x\2(1/40)wich is for b + x/2(1/24)wich is for both a and b.
So taking common we get x/2(1/40+1/24)=1 which 1 means to full whole tank.
Pankaj bansal said:
1 decade ago
Here,
B's 1 minute capacity is 1/40
A and B combined capacity is 1/24 to fill whole tank
Let x is total time
now x/2 X 1/40 { time for which B alone is works
and x/2 X 1/24 { time for which A and B both works
Now add both (as total time to flll the tank) and take common x/2
We get x/2(1/40 +1/24)=1 {1 is for full tank}
B's 1 minute capacity is 1/40
A and B combined capacity is 1/24 to fill whole tank
Let x is total time
now x/2 X 1/40 { time for which B alone is works
and x/2 X 1/24 { time for which A and B both works
Now add both (as total time to flll the tank) and take common x/2
We get x/2(1/40 +1/24)=1 {1 is for full tank}
Leonard said:
1 decade ago
this question is confused me because the real story would not be happen like that. please some one to explain it?
Suji said:
1 decade ago
Nothing to confuse last 2 lines of question is changed into eqn.
Given half time to fill. As we don't know min. We take as x ie. X/2.
A and B together+only B.
Given half time to fill. As we don't know min. We take as x ie. X/2.
A and B together+only B.
Manasa said:
1 decade ago
Thanks ishan. Well explained.
Santhosh said:
1 decade ago
Thank You Pankaj
Shubham said:
1 decade ago
But as calculated so both A and B will fill tank in 24min?
So what about this?
So what about this?
Viz said:
1 decade ago
x/2(only B) + x/2(A and B together) = 1.
x/2(1/40) + x/2 (1/60+1/40) = 1.
x/80 + x/2(5/120) = 1.
x/80 + 5x/240 = 1.
(3x+5x)/240 = 1.
8x = 240.
x=30 mins.
x/2(1/40) + x/2 (1/60+1/40) = 1.
x/80 + x/2(5/120) = 1.
x/80 + 5x/240 = 1.
(3x+5x)/240 = 1.
8x = 240.
x=30 mins.
SANJAY PAHADE said:
1 decade ago
A simple method for solving this problem without formula :
Firstly, For a 1/2 Minute i.e half-minute Pipe B is used so,
Now, remaining part of tank should be filled by both A and B in remaining 1/2 i.e half minute.
For which combined capacity of A and B have to used as both are working simultaneously.
Finally,
We have to add tank filled by B alone and A+B together.
So, required answer is 30 mins respectively.
Firstly, For a 1/2 Minute i.e half-minute Pipe B is used so,
1 1 1
- * - = -
2 40 80
Now, remaining part of tank should be filled by both A and B in remaining 1/2 i.e half minute.
For which combined capacity of A and B have to used as both are working simultaneously.
1 [ 1 1 ] 1
- * [ - + - ] = -
2 [ 40 80 ] 48
Finally,
We have to add tank filled by B alone and A+B together.
1 1 128
- + - = ---
80 48 3840
1
= -
30
So, required answer is 30 mins respectively.
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