Aug 18 07:00 AM PDT  09:00 AM PDT Attend this webinar to learn a structured approach to solve 700+ Number Properties question in less than 2 minutes. Aug 19 08:00 AM PDT  09:00 AM PDT Join a 4day FREE online boot camp to kick off your GMAT preparation and get you into your dream bschool in R1.**Limited for the first 99 registrants. Register today! Aug 20 08:00 PM PDT  09:00 PM PDT EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth $100 with the 3 Month Pack ($299) Aug 20 09:00 PM PDT  10:00 PM PDT Take 20% off the plan of your choice, now through midnight on Tuesday, 8/20 Aug 22 09:00 PM PDT  10:00 PM PDT What you'll gain: Strategies and techniques for approaching featured GMAT topics, and much more. Thursday, August 22nd at 9 PM EDT Aug 24 07:00 AM PDT  09:00 AM PDT Learn reading strategies that can help even nonvoracious reader to master GMAT RC
Author 
Message 
TAGS:

Hide Tags

Manager
Status: single
Joined: 19 Jan 2015
Posts: 84
Location: India
GPA: 3.2
WE: Sales (Pharmaceuticals and Biotech)

Re: A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
22 Aug 2015, 20:05
pool can be filled in 4 hours and drained 5 hours. take lcm of two pipes that is 20 units. takes 20 hours to fill pool if both the pipes opened simultaneously.
filling pipe can fill 5units/hour.
draing pipe take out 4units?hour. pool was opened at 1 pm. pool was filled at 11 pm. It takes 10 hours to complete it.
If drain pipe opened at 2 pm. filling pipe worked for 1 hour. so 5units work over. remaining 15 units take additional 15 hours to fill. if drain pipe opened at 2.30pm. filling pipe worked for 1 and 1/2 hour 7.5 units work over. take 12. 5 units , take additional 12.5 hours to fill. if drain pipe opened at 3 pm, 10 units units, over, 10 hours to fill. if drain pipe opened at 3.30pm. 12.5 units over, another 7.5 units , hours take to fill. 3.30+7.30= 11pm so option D is correct



Intern
Joined: 15 Feb 2015
Posts: 5

Re: A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
26 Aug 2015, 09:09
10/4  x/5 = 1 not 1/10



Senior Manager
Joined: 10 Mar 2013
Posts: 485
Location: Germany
Concentration: Finance, Entrepreneurship
GPA: 3.88
WE: Information Technology (Consulting)

A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
25 Nov 2015, 04:52
Economist wrote: This topic is locked. If you want to discuss this question please repost it in the respective forum. A pool can be filled in 4 hours and drained in 5 hours. The valve that fills the pool was opened at 1:00 pm and some time later the drain that empties the pool was also opened. If the pool was filled by 11:00 pm and not earlier, when was the drain opened? A. at 2:00 pm B. at 2:30 pm C. at 3:00 pm D. at 3:30 pm E. at 4:00 pm I did: 10/4  x/5 = 1/10 ( x = number of hours drain pipe is opened ). But I cant find the answer. m20 q32I would rather use here smart numbers.... Pool Capacity = 100 Liters Filling Rate (F) = \(\frac{100}{4}=25\) Draining Rate (D) = \(\frac{100}{5}=20\) Time =10 Hours (Start 1:00 pm End 11:00 pm) 250 Liters were filled in 10 hours > 10*Rate(F) so we have +150 Liters that must be drained (because the filled pool must have only 100 Liters) \(Rate (D) * t = 150\) > \(20*t=150\), \(t=7.5 Hours\) Answer D (11 pm  7.5 =3:30) Hope this approach helps....
_________________
When you’re up, your friends know who you are. When you’re down, you know who your friends are.
Share some Kudos, if my posts help you. Thank you !
800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50 GMAT PREP 670 MGMAT CAT 630 KAPLAN CAT 660



Intern
Joined: 06 Feb 2018
Posts: 16

Re: A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
26 Mar 2018, 10:42
BunuelIf the value was open for x hours, then why is it (111x) hours when both the valve and the drain were open and not just (11−x)hours? Thanks!



Math Expert
Joined: 02 Sep 2009
Posts: 57025

Re: A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
26 Mar 2018, 10:49
mahrah wrote: BunuelIf the value was open for x hours, then why is it (111x) hours when both the valve and the drain were open and not just (11−x)hours? Thanks! The valve was opened from 1:00 pm to 11:00 pm, so for 11  1 = 10 hours. If x is the amount of time when only the valve was open, then 10  x is the amount of time when both the valve and the drain were open.
_________________



VP
Joined: 07 Dec 2014
Posts: 1225

A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
26 Mar 2018, 11:11
Economist wrote: A pool can be filled in 4 hours and drained in 5 hours. The valve that fills the pool was opened at 1:00 pm and some time later the drain that empties the pool was also opened. If the pool was filled by 11:00 pm and not earlier, when was the drain opened?
A. at 2:00 pm B. at 2:30 pm C. at 3:00 pm D. at 3:30 pm E. at 4:00 pm let d=hours drain open 10*1/4d*1/5=1 d=7.5 hours 11:00 pm7.5 hours=3:30 pm D



eGMAT Representative
Joined: 04 Jan 2015
Posts: 3019

Re: A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
28 Mar 2018, 02:51
Solution Given: • The pool can be filled in 4 hours • The pool can be drained in 5 hours. • Filling valve was opened at 1:00 pm • The Pool was filled at 11:00 pm Working out: We need to find out the time when the drain valve was opened. Per our conceptual knowledge, we know that the total volume of the pool can be taken as the LCM of 4 and 5. Thus, let’s assume that the total volume of the pool = 20 Liters. Since the pool can be filled in 4 hours, in 1 hour, the amount of water filled in it = 5 litres. Similarly, the amount of water drained in 1 hour = 4 litres. Let’s also assume that the time after which the drain valve was opened = x hours. So, from 1 pm to (1+x) pm, the pool was being filled at the rate of 5 liters per hour. And from (1+x) pm to 11 pm, the pool was filled at a rate of (54) = 1 liter per hour. Thus, • 5*x+ 1(10x) = 20 • Or, 5x + 10 x = 20 • Or, 4x = 10 • Or, x =2.5 hours. Thus, the drain valve was opened at 1+ 2:30 hours = 3:30 pm. Answer: Option D
_________________



Intern
Joined: 07 Nov 2013
Posts: 13
Location: India
Concentration: Marketing, General Management
GPA: 3.77
WE: Consulting (Consulting)

Re: A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
31 Jul 2019, 20:38
Economist wrote: A pool can be filled in 4 hours and drained in 5 hours. The valve that fills the pool was opened at 1:00 pm and some time later the drain that empties the pool was also opened. If the pool was filled by 11:00 pm and not earlier, when was the drain opened? A. at 2:00 pm B. at 2:30 pm C. at 3:00 pm D. at 3:30 pm E. at 4:00 pm I did: 10/4  x/5 = 1/10 ( x = number of hours drain pipe is opened ). But I cant find the answer. m20 q32Quick Method Let the whole pool unit be 5 X 4 = 20 Filling per hour is 5 Draining per hour is 4 Pool was for sure filling from 1 PM to 11 PM which are 10 hours So, filling pipe started for 10 hours Work done by Filling Pipe = 50 Equation would be : 50 [Filling pipe ran for 10 hours 5 x 10 ]  4x [ Draining pipe ran for some hours ] = 20 [ both need to reach this much unit of pool ] Solving equation x = 7.5 [ Means Draining pipe ran for 7.5 hours out of 10 hours of filling operation ] Therefore , it should have started after 2.5 hours Hens Ans is 3:30 PM



Intern
Joined: 06 May 2019
Posts: 23
Location: India
Concentration: General Management, Marketing

Re: A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
03 Aug 2019, 04:15
Let the capacity be 100 litres
Filling rate20/hr draining rate: 25 /hr
Filling pipe worked for 10 hours Thus, 25*10=250 But, capacity is 100
150 must be drained by draining pipe Thus, it will take 150/20=7.5 hours to drain
Thus, it has started 2.5 hours after 1 pm
Thus, answer=3:30PM



VP
Joined: 07 Dec 2014
Posts: 1225

A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
Show Tags
03 Aug 2019, 17:25
Economist wrote: A pool can be filled in 4 hours and drained in 5 hours. The valve that fills the pool was opened at 1:00 pm and some time later the drain that empties the pool was also opened. If the pool was filled by 11:00 pm and not earlier, when was the drain opened?
A. at 2:00 pm B. at 2:30 pm C. at 3:00 pm D. at 3:30 pm E. at 4:00 pm in 10 hours with drain closed, valve can fill 10/4, or 2.5 pools so in 10 hours with valve open, drain must empty 2.51=1.5 pools 1.5 pools*5 hours=7.5 hours drain needs to leave pool filled at 11:00pm 11:00pm7.5 hours=3:30pm D




A pool can be filled in 4 hours and drained in 5 hours. The
[#permalink]
03 Aug 2019, 17:25



Go to page
Previous
1 2
[ 30 posts ]



