• NEW! FREE Beat The GMAT Quizzes
Hundreds of Questions Highly Detailed Reporting Expert Explanations
• 7 CATs FREE!
If you earn 100 Forum Points

Engage in the Beat The GMAT forums to earn
100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## The water from one outlet, flowing at a constant rate, can ##### This topic has 3 expert replies and 1 member reply ### Top Member ## The water from one outlet, flowing at a constant rate, can ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult The water from one outlet, flowing at a constant rate, can fill a swimming pool in 9 hours. The water from a second outlet, flowing at a constant rate, can fill the same pool in 5 hours. If both outlets are used at the same time, approximately what is the number of hours required to fill the pool? (A) 0.22 (B) 0.31 (C) 2.50 (D) 3.21 (E) 4.56 OA D Source: Official Guide ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 13038 messages Followed by: 1251 members Upvotes: 5254 GMAT Score: 770 BTGmoderatorDC wrote: The water from one outlet, flowing at a constant rate, can fill a swimming pool in 9 hours. The water from a second outlet, flowing at a constant rate, can fill the same pool in 5 hours. If both outlets are used at the same time, approximately what is the number of hours required to fill the pool? (A) 0.22 (B) 0.31 (C) 2.50 (D) 3.21 (E) 4.56 OA D Source: Official Guide So, let's say that the volume of the pool is 45 gallons. The water from one outlet, flowing at a constant rate, can fill a swimming pool in 9 hours So, this outlet pumps at a rate of 5 gallons per hour The water from a second outlet, flowing at a constant rate, can fill the same pool in 5 hours. So, this outlet pumps at a rate of 9 gallons per hour If both outlets are used at the same time. . . The combined rate of both pumps = (5 gallons per hour) + (9 gallons per hour) = 14 gallons per hour Time = output/rate At 14 gallons per hour, the time to pump 45 gallons = 45/14 = 3 3/14 = 3.something Answer: D Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use my video course along with Sign up for free Question of the Day emails And check out all of these free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 10197 messages Followed by: 497 members Upvotes: 2867 GMAT Score: 800 Hi All, This question is a standard "Work Formula" question. When you have 2 entities sharing a task, you can use the following formula to figure out how long it takes for the 2 entities to complete the task together. Work = (A)(B)/(A+B) where A and B are the individual times required to complete the task Here, we're given the rates as 9 hours and 5 hours. Using the Work Formula, we have... (9)(5)/(9+5) = 45/14 45/14 is a little more than 3.....there's only one answer that matches... Final Answer: D GMAT assassins aren't born, they're made, Rich _________________ Contact Rich at Rich.C@empowergmat.com ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2950 messages Followed by: 19 members Upvotes: 43 BTGmoderatorDC wrote: The water from one outlet, flowing at a constant rate, can fill a swimming pool in 9 hours. The water from a second outlet, flowing at a constant rate, can fill the same pool in 5 hours. If both outlets are used at the same time, approximately what is the number of hours required to fill the pool? (A) 0.22 (B) 0.31 (C) 2.50 (D) 3.21 (E) 4.56 OA D Source: Official Guide The combined rate of the first and second outlets is: 1/9 + 1/5 = 5/45 + 9/45 = 14/45 Thus, the combined fill rate is 14/45 of the pool in one hour. So the time it would take both outlets to fill the pool is 45/14 â‰ˆ 3.21 hours. Answer: D _________________ Scott Woodbury-Stewart Founder and CEO scott@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews ### Top Member Legendary Member Joined 02 Mar 2018 Posted: 1171 messages Followed by: 2 members For pipe 1 = Work done in 1 hour = 1/9 (rate) For pipe 2 = Work done in 1 hour = 1/5 (rate) Work done = Rate x Time $$1=\left(\frac{1}{9}+\frac{1}{5}\right)\cdot x$$ $$1=\frac{\left(5+9\right)}{45}\cdot x$$ $$1=\frac{14}{45}\cdot x$$ $$45=14\cdot x$$ $$x=\frac{45}{14}=3.21$$ Option D is correct..... • Award-winning private GMAT tutoring Register now and save up to$200

Available with Beat the GMAT members only code

• 5 Day FREE Trial
Study Smarter, Not Harder

Available with Beat the GMAT members only code

• Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• Get 300+ Practice Questions

Available with Beat the GMAT members only code

• 5-Day Free Trial
5-day free, full-access trial TTP Quant

Available with Beat the GMAT members only code

• Free Trial & Practice Exam
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• Free Veritas GMAT Class
Experience Lesson 1 Live Free

Available with Beat the GMAT members only code

• Free Practice Test & Review
How would you score if you took the GMAT

Available with Beat the GMAT members only code

• FREE GMAT Exam
Know how you'd score today for \$0

Available with Beat the GMAT members only code

### Top First Responders*

1 Ian Stewart 43 first replies
2 Brent@GMATPrepNow 35 first replies
3 Scott@TargetTestPrep 33 first replies
4 Jay@ManhattanReview 28 first replies
5 GMATGuruNY 19 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

### Most Active Experts

1 Scott@TargetTestPrep

Target Test Prep

149 posts
2 Max@Math Revolution

Math Revolution

93 posts
3 Brent@GMATPrepNow

GMAT Prep Now Teacher

53 posts
4 Ian Stewart

GMATiX Teacher

52 posts
5 GMATGuruNY

The Princeton Review Teacher

32 posts
See More Top Beat The GMAT Experts