Aptitude - Pipes and Cistern - Discussion
Discussion Forum : Pipes and Cistern - General Questions (Q.No. 3)
3.
A pump can fill a tank with water in 2 hours. Because of a leak, it took 2
hours to fill the tank. The leak can drain all the water of the tank in:
hours to fill the tank. The leak can drain all the water of the tank in:Answer: Option
Explanation:
| Work done by the leak in 1 hour = |  |
1 | - | 3 |  |
= | 1 | . |
| 2 | 7 | 14 |
Leak will empty the tank in 14 hrs.
Discussion:
90 comments Page 6 of 9.
Raja said:
1 decade ago
@Sai.
Its actually 1/(7/3).
Its actually 1/(7/3).
SAI TRIVENI said:
1 decade ago
As per question a pump can fill and due to leakage it took 1/3 of time extra.
As we can say {PUMP-(PUMP+LEAKAGE)== IF WE SIMPLEFY THIS == PUMP-PUMP-LEAKAGE THIS GIVE RESULT AS = -LEAKAGE.
I CAN'T UNDERSTAND WHY U REVERSED THE VALUE IT MUST BE 7/3 BUT U TOOK 3/7 HOW?
As we can say {PUMP-(PUMP+LEAKAGE)== IF WE SIMPLEFY THIS == PUMP-PUMP-LEAKAGE THIS GIVE RESULT AS = -LEAKAGE.
I CAN'T UNDERSTAND WHY U REVERSED THE VALUE IT MUST BE 7/3 BUT U TOOK 3/7 HOW?
Vinay arora said:
1 decade ago
In 120 mints it complete = 1 tank
but it take 140 mints now so,
in 1 mint it fill =1/120
extra time it take be= 140-120= 20 mints
in 20 mint it fill= 20 * (1/120) =1/6
1/6 tank fill in 2 Hr 20 mint that is 7/3 so
1/6 of tank fill= 7/3
1 tank fill in= (7/3)*6= 14 hr
ok buddy......
but it take 140 mints now so,
in 1 mint it fill =1/120
extra time it take be= 140-120= 20 mints
in 20 mint it fill= 20 * (1/120) =1/6
1/6 tank fill in 2 Hr 20 mint that is 7/3 so
1/6 of tank fill= 7/3
1 tank fill in= (7/3)*6= 14 hr
ok buddy......
Allhad said:
1 decade ago
To all who don't understand how 7/3.
Actually time given is 2hrs and 20min i.e. 2hrs+20min (1/3 hrs).
Actually time given is 2hrs and 20min i.e. 2hrs+20min (1/3 hrs).
Raj said:
1 decade ago
It is very simple.
Pump takes 2hr to fill
& due to leakage it takes 7/3 hrs
calculate it in terms of 1 hr.
pump will fill 1/2 part of tank
& due to leakage 3/7 part of tank
so leakage in 1 hr will be
1/2 - 3/7 = 1/14 part,
so full tank will be empty in
14 hr.
Pump takes 2hr to fill
& due to leakage it takes 7/3 hrs
calculate it in terms of 1 hr.
pump will fill 1/2 part of tank
& due to leakage 3/7 part of tank
so leakage in 1 hr will be
1/2 - 3/7 = 1/14 part,
so full tank will be empty in
14 hr.
Deepi said:
1 decade ago
A takes 2 hrs lets take as x
Leakage time lets y
2 1/3 hrs=7/3hrs
=> (x*y)/(y-x)=7/3
=> (2y)/(y-2)=7/3
=> 2y=(y-2)(7/3)
=> 2y=(7y/3)-14/3
=> -y/3=-14/3
=> y=14
Leakage time lets y
2 1/3 hrs=7/3hrs
=> (x*y)/(y-x)=7/3
=> (2y)/(y-2)=7/3
=> 2y=(y-2)(7/3)
=> 2y=(7y/3)-14/3
=> -y/3=-14/3
=> y=14
Ashu said:
1 decade ago
@chakri
If you take 7/3 hrs to complete 1 job
Then, what length of job will you take to complete in 1 hour
( what you do here is...use reciprocal value when u shift the value)
that is
7/3=>1
1=>3/7
If you take 7/3 hrs to complete 1 job
Then, what length of job will you take to complete in 1 hour
( what you do here is...use reciprocal value when u shift the value)
that is
7/3=>1
1=>3/7
Sandeep said:
1 decade ago
Lets us simplify by doing it minute basis:.
Let the Volume be V without leak tank is filled in 120 min.
So, in 1 min = V/120.
With leak, = V/140.
Leak is withdrawing water per min = V/120 - V/140 = V/840.
i.e 840th part is filled in 1 min.
So the tank is filled in 840 min i.e. 14 hours.
----------------------------------------------------------------Hour Basis,
In 1 hour V/2 with leak, 3V/7.
Work by leak = V/2-3V/7 = V/14.
V = 14 h.
Let the Volume be V without leak tank is filled in 120 min.
So, in 1 min = V/120.
With leak, = V/140.
Leak is withdrawing water per min = V/120 - V/140 = V/840.
i.e 840th part is filled in 1 min.
So the tank is filled in 840 min i.e. 14 hours.
----------------------------------------------------------------Hour Basis,
In 1 hour V/2 with leak, 3V/7.
Work by leak = V/2-3V/7 = V/14.
V = 14 h.
Chakri said:
1 decade ago
Please tell me why it's 7/3 changed into 3/7?
PGCR ( Sri Lanka) said:
1 decade ago
Just because of the leak it took 2 1/3 hours.
Normally it takes only 2 hours.
Hence,
1 1 1
- - - = -
2 X (2 1/3)
OR
1 1 1
- - - = -
2 (2 1/3) X
So, X = 14 hours.
Normally it takes only 2 hours.
Hence,
1 1 1
- - - = -
2 X (2 1/3)
OR
1 1 1
- - - = -
2 (2 1/3) X
So, X = 14 hours.
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