Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 23 Aug 2011
Posts: 61

Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
Updated on: 05 Dec 2016, 09:25
Question Stats:
68% (02:41) correct 32% (02:48) wrong based on 287 sessions
HideShow timer Statistics
Tap A can fill a tank in 36 minutes, Tap B can fill the same tank in 48 minutes. If they are opened simultaneously, at what time tap B (keep tap A running) can be stopped so that the tank can be filled completely filled in 27 minutes. A. 8 B. 12 C. 20 D. 30 E. 36 This question was asked by one of the tutor who was giving presentation on a local GMAT prep course.I cannot remember the options exactly, but all options were integers. I guess b/w (1240).If the question sounds awkward or has other flaws please feel free to provide inputs/correct it.I am looking for its solution and similar rate problems in which 2 entities work together for some portion and then one of 'em leaves.
Official Answer and Stats are available only to registered users. Register/ Login.
Originally posted by conty911 on 27 Sep 2012, 09:21.
Last edited by bb on 05 Dec 2016, 09:25, edited 1 time in total.
Added answer choices




Intern
Joined: 02 Nov 2009
Posts: 30
Location: India
Concentration: General Management, Technology
GMAT Date: 04212013
GPA: 4
WE: Information Technology (Internet and New Media)

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
27 Sep 2012, 09:25
Tap A can fill a tank in 36 minutes which means that 1/36th of the tank will be filled up in a minute Tap B can fill a tank in 48minutes which means that 1/48th of the tank will be filled up in a minute and Given that A is open for 27 min > 27/36 or 3/4 of the tank will be filled and B has to fill the remaing 1/4th of the tank. B will fill the enitre tank in 48 mins and for it to fill 1/4 th of the tank it will take (48/4)12 mins.
_________________




Manager
Joined: 23 Aug 2011
Posts: 61

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
27 Sep 2012, 09:35
abhishekkpv wrote: Tap A can fill a tank in 36 minutes which means that 1/36th of the tank will be filled up in a minute Tap B can fill a tank in 48minutes which means that 1/48th of the tank will be filled up in a minute
and Given that A is open for 27 min > 27/36 or 3/4 of the tank will be filled and B has to fill the remaing 1/4th of the tank.
B will fill the enitre tank in 48 mins and for it to fill 1/4 th of the tank it will take (48/4)12 mins. Thanks that helps kudos to you .



Intern
Joined: 31 May 2012
Posts: 7

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
27 Sep 2012, 15:28
conty911 wrote: Tap A can fill a tank in 36 minutes, Tap B can fill the same tank in 48 minutes. If they are opened simultaneously, at what time tap B (keep tap A running) can be stopped so that the tank can be filled completely filled in 27 minutes. This question was asked by one of the tutor who was giving presentation on a local GMAT prep course.I cannot remember the options exactly, but all options were integers. I guess b/w (1240).If the question sounds awkward or has other flaws please feel free to provide inputs/correct it.I am looking for its solution and similar rate problems in which 2 entities work together for some portion and then one of 'em leaves. You can also use two equations provided: (1/36 + 1/48)t1 + (1/36)t2 =1 t1 + t2 = 27 > t2 = 27  t1 (1/36 + 1/48)t1 + (1/36)(27  t1) = 1 t1 = 12



Intern
Status: Preparing for GMAT
Joined: 19 Sep 2012
Posts: 16
Location: India
GMAT Date: 01312013
WE: Information Technology (Computer Software)

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
25 Oct 2012, 06:32
A to be opened for 27 mins that is 27/36 =3/4 of the tank is filled..
so remaining 1/4th of tank to be filled by B
48 /4 = 12 mins to fill 1/4 of the remaining...(logic is 1/4 =x/48) !!



GMAT Tutor
Status: Private GMAT Tutor
Joined: 22 Oct 2012
Posts: 154
Location: India
Concentration: Economics, Finance
GMAT 1: 780 Q51 V47

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
25 Oct 2012, 17:59
abhishekkpv wrote: Tap A can fill a tank in 36 minutes which means that 1/36th of the tank will be filled up in a minute Tap B can fill a tank in 48minutes which means that 1/48th of the tank will be filled up in a minute
and Given that A is open for 27 min > 27/36 or 3/4 of the tank will be filled and B has to fill the remaing 1/4th of the tank.
B will fill the enitre tank in 48 mins and for it to fill 1/4 th of the tank it will take (48/4)12 mins. Very good way of thinking. +1 Cheers, CJ
_________________



Intern
Joined: 30 Jun 2010
Posts: 7

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
02 Nov 2012, 02:10
conty911 wrote: Tap A can fill a tank in 36 minutes, Tap B can fill the same tank in 48 minutes. If they are opened simultaneously, at what time tap B (keep tap A running) can be stopped so that the tank can be filled completely filled in 27 minutes. I would approach this question in some other way, since it says that the taps are opened simultaneously, and the question asks what time tap B can be stopped at interval "after both taps have been opened for some time" so that the entire tank can be filled in 27 minutes ( not running tap A for addition 27 minutes). 1. find the combined rate of two taps (since they are opened simultaneously): work/time>>> (1/36+1/48) = 6/144, meaning that combined rate is 144/6 = 24 minutes (both taps can fill up the tank in 24 minutes if with no pause on either tap). 2. let T be the time that tap B can be stopped. we can form the work formula letting a+b run together for T + tap A alone continues running for 27T (since total time is 27 minutes) = 1 (filling up the tank) the equation looks like this : (1/24)T + (1/36)(27T) = 1 >>> 3T/72 +(542T)/72 = 1 solve this equation you will get T = 18 minutes, the time that tap B can be stopped so that tank can be filled in 27 minutes, which is the answer. in this case, tap A alone will continue running for 9 minutes to fill up the tank.



Senior Manager
Joined: 13 Aug 2012
Posts: 392
Concentration: Marketing, Finance
GPA: 3.23

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
14 Nov 2012, 03:42
Rate of B x time + Rate of A x 27 minutes = 1 (combined output of Tap A and B) \(\frac{1}{48} t + \frac{27}{36}= 1\) \(\frac{1}{48} t = 1  \frac{3}{4}\) \(\frac{1}{48} t = \frac{1}{4}\)
t = 12 minutes



Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4876
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
21 Nov 2016, 08:02
conty911 wrote: Tap A can fill a tank in 36 minutes, Tap B can fill the same tank in 48 minutes. If they are opened simultaneously, at what time tap B (keep tap A running) can be stopped so that the tank can be filled completely filled in 27 minutes. Let the volume be = 144 Efficiency of A = 4 Efficiency of B = 3 Combinedd efficiency of A & B = 7 7*( 27  t ) + 4t = 144 189 7t + 4t = 144 Or, 3t = 45 So, t = 15 Thus tap B must be stopped after 12 ( ie, 27  15) minutes
_________________



Founder
Joined: 04 Dec 2002
Posts: 19430
Location: United States (WA)
GPA: 3.5

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
05 Dec 2016, 09:26
Added answer choices to the question. Thank you for reporting it.
_________________



Intern
Joined: 23 Jun 2017
Posts: 10

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
12 Feb 2018, 20:21
[quote="conty911"]Tap A can fill a tank in 36 minutes, Tap B can fill the same tank in 48 minutes. If they are opened simultaneously, at what time tap B (keep tap A running) can be stopped so that the tank can be filled completely filled in 27 minutes.
A. 8 B. 12 C. 20 D. 30 E. 36
Ans. Let the volume be = 144
Efficiency of A = 4 Efficiency of B = 3
Tap A will run for 27 minutes so 27*4 = 108 units done Remaining units will be done by B that is 36/3 = 12 minutes Tap B will work for 12 minutes.



Intern
Joined: 05 Jun 2018
Posts: 1

Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
Updated on: 05 Jun 2018, 02:09
grandtheman wrote: conty911 wrote: Tap A can fill a tank in 36 minutes, Tap B can fill the same tank in 48 minutes. If they are opened simultaneously, at what time tap B (keep tap A running) can be stopped so that the tank can be filled completely filled in 27 minutes. I would approach this question in some other way, since it says that the taps are opened simultaneously, and the question asks what time tap B can be stopped at interval "after both taps have been opened for some time" so that the entire tank can be filled in 27 minutes ( not running tap A for addition 27 minutes). 1. find the combined rate of two taps (since they are opened simultaneously): work/time>>> (1/36+1/48) = 6/144, meaning that combined rate is 144/6 = 24 minutes (both taps can fill up the tank in 24 minutes if with no pause on either tap). 2. let T be the time that tap B can be stopped. we can form the work formula letting a+b run together for T + tap A alone continues running for 27T (since total time is 27 minutes) = 1 (filling up the tank) the equation looks like this : (1/24)T + (1/36)(27T) = 1 >>> 3T/72 +(542T)/72 = 1 solve this equation you will get T = 18 minutes, the time that tap B can be stopped so that tank can be filled in 27 minutes, which is the answer. in this case, tap A alone will continue running for 9 minutes to fill up the tank. Your calculation is wrong at the first step: (1/36+1/48) = 6/144 this is not right. (1/36+1/48) = 7/144 So eventually you will also get 12 minutes as answer. "Approaches can be different in maths, but the answer remains same."
Originally posted by rajsinghudr on 05 Jun 2018, 01:09.
Last edited by rajsinghudr on 05 Jun 2018, 02:09, edited 1 time in total.



Senior PS Moderator
Joined: 26 Feb 2016
Posts: 3260
Location: India
GPA: 3.12

Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
05 Jun 2018, 02:05
rajsinghudr wrote: grandtheman wrote: conty911 wrote: Tap A can fill a tank in 36 minutes, Tap B can fill the same tank in 48 minutes. If they are opened simultaneously, at what time tap B (keep tap A running) can be stopped so that the tank can be filled completely filled in 27 minutes. I would approach this question in some other way, since it says that the taps are opened simultaneously, and the question asks what time tap B can be stopped at interval "after both taps have been opened for some time" so that the entire tank can be filled in 27 minutes ( not running tap A for addition 27 minutes). 1. find the combined rate of two taps (since they are opened simultaneously): work/time>>> (1/36+1/48) = 6/144, meaning that combined rate is 144/6 = 24 minutes (both taps can fill up the tank in 24 minutes if with no pause on either tap). 2. let T be the time that tap B can be stopped. we can form the work formula letting a+b run together for T + tap A alone continues running for 27T (since total time is 27 minutes) = 1 (filling up the tank) the equation looks like this : (1/24)T + (1/36)(27T) = 1 >>> 3T/72 +(542T)/72 = 1 solve this equation you will get T = 18 minutes, the time that tap B can be stopped so that tank can be filled in 27 minutes, which is the answer. in this case, tap A alone will continue running for 9 minutes to fill up the tank. Your calculation is wrong at the first step: (1/36+1/48) = 6/144 this is not right. (1/36+1/48) = 7/144 So eventually you will also get 12 minutes as answer. "Approaches can be different in maths, but the answer will only be one." Hey rajsinghudrAppreciate the effort but grandtheman posted that post in 2012 Btw, Welcome to GMATClub. All the best with your GMAT journey!
_________________
You've got what it takes, but it will take everything you've got



Manager
Joined: 30 Jun 2019
Posts: 150

Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
Show Tags
30 Jan 2020, 15:53
1=(1/36 + 1/48)t1 + (1/36)t2 1= 1/36(t1+t2) + (1/48)t1 1= 1/36(27) + (1/48)t1 1= 27/48 + t1/48 127/48=t1/48 1/4 = t1/48 12 = t1
B




Re: Tap A can fill a tank in 36 minutes, Tap B can fill the same
[#permalink]
30 Jan 2020, 15:53






