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tank filling # time taken

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by albatross86 » Tue Jun 29, 2010 4:46 am
Identical taps = same rate

First 20 minutes was at twice the rate
Next T minutes would be at only one rate

=> 2R*20 = 2/5C

=> R = C/100

And for the rest of the tank we have:

=> R*T = 3/5C

Substituting value of R:

=> C/100 * T = 3/5 C

=> T = 60 minutes
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by selango » Tue Jun 29, 2010 6:14 am
Tap A complete work in X minutes.So in 1 min it complete 1/X unit of work.

similarly Tap B complete 1/X unit of work in 1 min.[Same rate for both taps]

20*(1/x+1/x)=2/5

20*(2/x)=2/5

x=100

Now Tap A fill 3/5 of tank and T be number of minutes

T*(1/100)=3/5

T=60 mins
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by [email protected] » Tue Jun 29, 2010 7:47 am
Two identical taps fill 2/5 of a tank in 20 minutes. When one of the taps goes dry in how many minutes will the
remaining one tap fill the rest of the tank ?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 20 minutes
E. None of the above
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by selango » Tue Jun 29, 2010 7:51 am
Its option E
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by Haaress » Tue Jun 29, 2010 7:59 am
Ofcourse one can use the algebraic method to solve this question, but I guess the quickest method is logic in this case.

If 2 taps can fill 2/5 in 20 minutes, then 1 tap fills 1/5 in 20 minutes.

So give the tank is 2/5 full, the remaining part s 3/5. The only running tap takes 20 minutes to fill 1/5, so it will take 20(3) to fill 1/5 (3) .

Thus 60 minutes or E in this case.
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by amising6 » Tue Jun 29, 2010 8:05 am
[email protected] wrote:Two identical taps fill 2/5 of a tank in 20 minutes. When one of the taps goes dry in how many minutes will the
remaining one tap fill the rest of the tank ?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 20 minutes
E. None of the above
so both the taps filling individually 1/5 in 20 minutes
tank to be filled 4/5
now one of them will fill reamining 4/5 in 20*4=80 mins
Ideation without execution is delusion
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by selango » Tue Jun 29, 2010 8:09 am
amising6 wrote:
[email protected] wrote:Two identical taps fill 2/5 of a tank in 20 minutes. When one of the taps goes dry in how many minutes will the
remaining one tap fill the rest of the tank ?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 20 minutes
E. None of the above
so both the taps filling individually 1/5 in 20 minutes
tank to be filled 4/5
now one of them will fill reamining 4/5 in 20*4=80 mins

amising6,

already 2/5 of tank is filled.Remaining 3/5 of tank only need to be filled.

3/5=3*1/5=3*20=60
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by amising6 » Tue Jun 29, 2010 8:19 am
selango wrote:
amising6 wrote:
[email protected] wrote:Two identical taps fill 2/5 of a tank in 20 minutes. When one of the taps goes dry in how many minutes will the
remaining one tap fill the rest of the tank ?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 20 minutes
E. None of the above
so both the taps filling individually 1/5 in 20 minutes
tank to be filled 4/5
now one of them will fill reamining 4/5 in 20*4=80 mins
ohh yes thanks


amising6,

already 2/5 of tank is filled.Remaining 3/5 of tank only need to be filled.

3/5=3*1/5=3*20=60
Ideation without execution is delusion
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