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 4 of 6.
Siddhesh said:
8 years ago
(A+B) & B are not working simultaneously, one of them assume B first work for say x minutes and fill some part of tank.
According to question other (A+B) also work for x minute to fill the remaining part.
The part filled by B in x minutes = x/40,
part filled by (A+B) in x minutes.
= x/24
(x/40) + (x/24)=1
x =15
So total time is 2x = 30 min.
According to question other (A+B) also work for x minute to fill the remaining part.
The part filled by B in x minutes = x/40,
part filled by (A+B) in x minutes.
= x/24
(x/40) + (x/24)=1
x =15
So total time is 2x = 30 min.
(1)
Emon said:
8 years ago
Check the question. It is said half the time. So the answer is 30.
If it is said half of the tanker then the answer would be 32.
If it is said half of the tanker then the answer would be 32.
(1)
Ayush said:
8 years ago
Here if you do it by simple LCM method u will get 32 answers but if you take 1 minute alternate for both u will get 30 answers as;
(3+5) = 2 minute cycle.
=120(lcm of 60 nd 40)/8 = 30minutes.
(3+5) = 2 minute cycle.
=120(lcm of 60 nd 40)/8 = 30minutes.
Raj karan said:
8 years ago
Well explained, thanks @Ayush.
Rohit said:
8 years ago
LCM of 60 and 40 is 120.
So a 1 min work is 120/60=2.
And b 1 min work is 120/40=3.
After getting 1 min work by LCM as A=2 and b=3..consider full time as x so the halftime will be x/2.
So,
3x/2 + (2+3)x/2=120...solving it u get x=30.
Here 120 is taken on right because it's the total quantity.
So a 1 min work is 120/60=2.
And b 1 min work is 120/40=3.
After getting 1 min work by LCM as A=2 and b=3..consider full time as x so the halftime will be x/2.
So,
3x/2 + (2+3)x/2=120...solving it u get x=30.
Here 120 is taken on right because it's the total quantity.
(1)
Santosh said:
7 years ago
The answer is 32. I agree with this.
(1)
Bibin said:
7 years ago
LCM of 60 and 40 is 120.(total work=120).
So the efficiencies are 2 and 3.
A:B=2:3.
A+B=5 (combined efficiency).
Then consider the total time required to fill the tank as X.
B is used for half of the time and then A and B fill it together for the other half.then we can write as,
(X/2) x 5 + (X/2) x 3 = 120.
By solving this equation you will get X = 30.
So the efficiencies are 2 and 3.
A:B=2:3.
A+B=5 (combined efficiency).
Then consider the total time required to fill the tank as X.
B is used for half of the time and then A and B fill it together for the other half.then we can write as,
(X/2) x 5 + (X/2) x 3 = 120.
By solving this equation you will get X = 30.
(2)
Soham said:
7 years ago
The answer is wrong.
The question didn't ask, they did in halftime, the question asked they did the half work. So let's solve it simple way.
40 minty tea for full work for B, so 20 minutes for half work for B.
24 minutes for both AandB, so 12 minutes for half work for B.
SO TOTAL TIME TAKEN IS 20+12=32 minutes, 30 is wrong answer.
The question didn't ask, they did in halftime, the question asked they did the half work. So let's solve it simple way.
40 minty tea for full work for B, so 20 minutes for half work for B.
24 minutes for both AandB, so 12 minutes for half work for B.
SO TOTAL TIME TAKEN IS 20+12=32 minutes, 30 is wrong answer.
(1)
Anis said:
7 years ago
That means A take halftime but B take full time.
Let's total time t.
So, t/ 2(1/60) + t/ 40=1.
So, t= 30 minutes.
Let's total time t.
So, t/ 2(1/60) + t/ 40=1.
So, t= 30 minutes.
(2)
Bhavadip Gothadiya said:
7 years ago
The answer May be 32.
LCM of 40 and 60 (240).
tank A one minutes ( 240/60)==4.
tank B one minutes (240/40)==6.
The half Filled by Tank B.
120/6 === 20 Minutes.
Half filled together.
120/10 === 12 minutes.
Here maybe 32 answer
anyone Explain to me please why not 32?
LCM of 40 and 60 (240).
tank A one minutes ( 240/60)==4.
tank B one minutes (240/40)==6.
The half Filled by Tank B.
120/6 === 20 Minutes.
Half filled together.
120/10 === 12 minutes.
Here maybe 32 answer
anyone Explain to me please why not 32?
(2)
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