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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 22 Mar 2021, 07:45
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C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

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65% (hard)

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64% (02:57) correct 36% (03:07) wrong based on 229 sessions

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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 8/15 hours. Both the taps are turned on simultaneously. After how much time should Tap B be turned off so that the pool is filled completely in 18 minutes?

A 6 minutes
B 7 minutes
C 8 minutes
D 10 minutes
E 11 minutes
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C
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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 25 Mar 2021, 00:34
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Bunuel
Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 8/15 hours. Both the taps are turned on simultaneously. After how much time should Tap B be turned off so that the pool is filled completely in 18 minutes?

A 6 minutes
B 7 minutes
C 8 minutes
D 10 minutes
E 11 minutes
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Check out discussion on rates here:
https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/catego ... om/?s=rate

A takes 0.4 hrs = .4 * 60 = 24 mins to do the work alone
B takes 8/15 hrs = 8/15 * 60 = 32 mins to do the work alone

A works for the whole time of 18 mins so it completes 18/24 = 3/4th of the work.

B does the rest 1/4th of the work in whatever time it is on.
Time = Work/Rate = (1/4) / (1/32) = 8 mins

Answer (C)
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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 22 Mar 2021, 10:15
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Time A takes to fill .4*60; 24 mins and Time B takes 8/15*60; 32 mins
In 18 mins A fills 1/24* 18; 3/4 tank no B has to fill 1/4 of tank which it would fill in 32/4;8 mins
Option C

Bunuel
Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 8/15 hours. Both the taps are turned on simultaneously. After how much time should Tap B be turned off so that the pool is filled completely in 18 minutes?

A 6 minutes
B 7 minutes
C 8 minutes
D 10 minutes
E 11 minutes
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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 24 Mar 2021, 20:16
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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 8/15 hours. Both the taps are turned on simultaneously. After how much time should Tap B be turned off so that the pool is filled completely in 18 minutes?

Rate (Pool/min)
A: \(\frac{1}{(0.4·60)}=\frac{1}{24}\)
B: \(\frac{1}{\frac{8}{15}·60}=\frac{1}{(8·4)}=\frac{1}{32}\)
A+B: \(\frac{1}{32}+\frac{1}{24}=\frac{(24+32)}{(32·24)}=\frac{56}{(32·24)}=\frac{7}{96}\)

Work=Rate·Time
\(1=\frac{7}{96}(x)+\frac{1}{24}(18-x)\)
\(1=\frac{7x}{96}+\frac{3}{4}-\frac{x}{24}\)
\(\frac{1}{4}=\frac{7x}{96}-\frac{4x}{96}\)
\(\frac{1}{4}=\frac{3x}{96}=\frac{x}{32}\)
32=4x
x=8
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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 19 May 2022, 23:45
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Tap A can fill a tank in 24 minutes which means that 1/24th of the tank will be filled up in a minute
Tap B can fill a tank in 32 minutes which means that 1/32nd of the tank will be filled up in a minute

and given that A is open for 18 mins --> 18/24 or 3/4th of the tank will be filled and B has to fill the remaining 1/4th of the tank.

B will fill the entire tank in 32 mins and for it to fill 1/4 th of the tank it will take (32/4) = 8 mins.


Bunuel
Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 8/15 hours. Both the taps are turned on simultaneously. After how much time should Tap B be turned off so that the pool is filled completely in 18 minutes?

A 6 minutes
B 7 minutes
C 8 minutes
D 10 minutes
E 11 minutes
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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 20 May 2022, 13:43
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Since the time taken to fill the pool completely is given in minutes, convert the times taken by the individual taps to minutes.

0.4 hours = \(\frac{2}{5}\) hours = \(\frac{2}{5}\) * 60 = 24 minutes

\(\frac{8}{15}\) hours = \(\frac{8}{15}\) * 60 = 32 minutes

Let the capacity of the pool = LCM (24, 32) = 96 gallons
Therefore,
Rate at which Tap A fills the pool = \(\frac{96 }{ 24}\) = 4 gallons per minute

Rate at which Tap B fills the pool = \(\frac{96 }{ 32}\) = 3 gallons per minute

Let the time after which Tap B has to be turned off = x minutes
This means that both taps worked simultaneously for x minutes
Rate at which Tap A and B fill the pool when working simultaneously = 4 + 3 = 7 gallons per minute.

Since they worked simultaneously for x minutes, work done by them = 7x gallons
After Tap B was shut off, Tap A worked alone for (18 – x) minutes since the total time taken to fill the pool is 18 minutes

Therefore, 7x + 4 (18 – x) = 96
Solving the equation for x, we have x = 8

Tap B should be turned off after 8 minutes

The correct answer option is C.
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Tap A can fill a pool in 0.4 hours and Tap B can fill the same pool in 10 Jun 2025, 19:42
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