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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 ## Pipe A runs 30 liters of water per minute into a pool that tagged by: AAPL ##### This topic has 3 expert replies and 0 member replies ### Top Member ## Pipe A runs 30 liters of water per minute into a pool that ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Economist GMAT Pipe A runs 30 liters of water per minute into a pool that has a total volume of 3,600 liters. Pipe B fill a third of the pool in 6 hours. Working together how long will it take both pipes to fill the pool? A. 2 hours and 36 minutes B. 1.5 hours C. 9 hours and 12 minutes D. 15 hours E. 1 hour and 48 minutes OA E. ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12906 messages Followed by: 1248 members Upvotes: 5254 GMAT Score: 770 AAPL wrote: Economist GMAT Pipe A runs 30 liters of water per minute into a pool that has a total volume of 3,600 liters. Pipe B fill a third of the pool in 6 hours. Working together how long will it take both pipes to fill the pool? A. 2 hours and 36 minutes B. 1.5 hours C. 9 hours and 12 minutes D. 15 hours E. 1 hour and 48 minutes OA E. Let's determine the COMBINED RATE of the two pipes Given: Pipe A's RATE = 30 liters per minute This is equivalent to 1800 liters per HOUR Pipe B fills a third of the pool in 6 hours So, Pipe B fills the ENTIRE pool (3600 liters) in 18 hours Rate = Output/time = 3600/18 = 200 liters per hour COMBINED RATE = 1800 + 200 = 2000 liters per hour Working together how long will it take both pipes to fill the pool? Time = output/rate = 3600/2000 = 36/20 hours = 9/5 hours = 1 4/5 hours = 1 hour and 48 minutes = E Cheers, Brent _________________ Brent Hanneson – 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 GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months! ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2595 messages Followed by: 18 members Upvotes: 43 AAPL wrote: Economist GMAT Pipe A runs 30 liters of water per minute into a pool that has a total volume of 3,600 liters. Pipe B fill a third of the pool in 6 hours. Working together how long will it take both pipes to fill the pool? A. 2 hours and 36 minutes B. 1.5 hours C. 9 hours and 12 minutes D. 15 hours E. 1 hour and 48 minutes The combined rate of pipes A and B is: 30/(1/60) + (1/3 x 3600)/6 = 1800 + 1200/6 = 1800 + 200 = 2000 liters per hour. Thus, it will take 3600/2000 = 36/20 = 9/5 = 1 4/5 hours = 1 hour and 48 minutes to fill the pool when the two pipes work together. Alternate Solution: Pipe A’s rate is 30 liters per minute, or 1800 liters per hour. Pipe B’s rate is 1,200 liters in 6 hours, or 200 liters per hour. Thus, their combined hourly rate is 1800 + 200 = 2000 liters. Thus, it will take 3600/2000 = 36/20 = 9/5 = 1 4/5 hours = 1 hour and 48 minutes to fill the pool when the two pipes work together. Answer: E ### GMAT/MBA Expert GMAT Instructor Joined 09 Oct 2010 Posted: 1449 messages Followed by: 32 members Upvotes: 59 AAPL wrote: Economist GMAT Pipe A runs 30 liters of water per minute into a pool that has a total volume of 3,600 liters. Pipe B fill a third of the pool in 6 hours. Working together how long will it take both pipes to fill the pool? A. 2 hours and 36 minutes B. 1.5 hours C. 9 hours and 12 minutes D. 15 hours E. 1 hour and 48 minutes $$?\,\,\,:\,\,\,{\rm{time}}\,\,{\rm{together}}\,\,{\rm{for}}\,\,3600\,\,{\rm{liters}}$$ Let´s use UNITS CONTROL, one of the most powerful tools of our method! $$\left. \matrix{ A\,\,:\,\,\,{{30\,\,{\rm{liters}}} \over {\,1\,\,{\rm{minute}}\,}}\,\,\,\, \Rightarrow \,\,\,\,{{90\,\,{\rm{liters}}} \over {\,3\,\,{\rm{minutes}}\,}} \hfill \cr B\,\,:\,\,\,\,{{1200\,\,{\rm{liters}}} \over {\,6\,\,{\rm{hours}}\,}}\,\,\,\left( {{{1\,\,{\rm{hour}}} \over {\,60\,\,{\rm{minutes}}\,}}} \right)\,\, = \,\,{{10\,\,{\rm{liters}}} \over {\,3\,\,{\rm{minutes}}\,}}\,\,\, \hfill \cr} \right\}\,\,\,\,\,\, \Rightarrow \,\,\,\,?\,\,\, = \,\,\,3600\,\,{\rm{liters}}\,\,\,\,\left( {{{3\,\,{\rm{minutes}}} \over {\,90 + 10\,\,{\rm{liters}}\,}}} \right)\,\,\, = \,\,\,108\min \,\,\, = \,\,\left( {60 + 48} \right)\,\,\min$$ This solution follows the notations and rationale taught in the GMATH method. Regards, Fabio. _________________ Fabio Skilnik :: GMATH method creator ( Math for the GMAT) English-speakers :: https://www.gmath.net Portuguese-speakers :: https://www.gmath.com.br • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

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