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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 Tom drives from town A to town B, driving at a constant tagged by: BTGmoderatorLU This topic has 4 expert replies and 0 member replies Top Member Tom drives from town A to town B, driving at a constant Timer 00:00 Your Answer A B C D E Global Stats Difficult Source: Economist GMAT Tom drives from town A to town B, driving at a constant speed of 60 miles per hour. From town, B Tom immediately continues to town C. The distance between A and B is twice the distance between B and C. If the average speed of the whole journey was 36 mph, then what is Tom's speed driving from B to C in miles per hour? A. 12 B. 20 C. 24 D. 30 E. 36 The OA is B. GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1984 messages Followed by: 30 members Upvotes: 470 BTGmoderatorLU wrote: Source: Economist GMAT Tom drives from town A to town B, driving at a constant speed of 60 miles per hour. From town, B Tom immediately continues to town C. The distance between A and B is twice the distance between B and C. If the average speed of the whole journey was 36 mph, then what is Tom's speed driving from B to C in miles per hour? A. 12 B. 20 C. 24 D. 30 E. 36 The OA is B. The situation is depicted below. A -------------------60 mph / 2D miles -----------------------B-----------x mph / D miles------------C Say the distance of BC = x miles, thus, the distance AB = 2x miles. Say the speed between BC is x miles. â€¢ Time taken to travel AC = 3D/36 = D/12 hours; â€¢ Time taken to travel AB = 2D/60 = D/30 hours; â€¢ Time taken to travel BC = D/x = D/x hours => D/12 = D/30 + D/x 1/12 = 1/30 + 1/x => x = 20 mph The correct answer: B Hope this helps! -Jay _________________ Manhattan Review GMAT Prep Locations: Hyderabad | Kukatpally | Bangalore | Anna Nagar | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15362 messages Followed by: 1866 members Upvotes: 13060 GMAT Score: 790 BTGmoderatorLU wrote: Source: Economist GMAT Tom drives from town A to town B, driving at a constant speed of 60 miles per hour. From town, B Tom immediately continues to town C. The distance between A and B is twice the distance between B and C. If the average speed of the whole journey was 36 mph, then what is Tom's speed driving from B to C in miles per hour? A. 12 B. 20 C. 24 D. 30 E. 36 Let the distance between A and B = 120 miles. Since the 120-mile distance between A and B is twice the distance between B and C, the distance between B and C = 60 miles, implying that the total distance = 120+60 = 180 miles. Since the average speed for the 120-mile leg between A and B = 60 mph, the time to travel from A to B = d/r = 120/60 = 2 hours. Since the average speed for the entire 180-mile trip = 36 mph, the time to travel the entire trip = d/r = 180/36 = 5 hours. Time to travel from B to C = (time for the entire trip) - (time to travel from A to B) = 5-2 = 3 hours. Since it takes 3 hours to travel the 60-mile leg between B and C, the driving speed from B to C = d/t = 60/3 = 20 mph. The correct answer is B. _________________ Mitch Hunt Private Tutor for the GMAT and GRE GMATGuruNY@gmail.com If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. Student Review #1 Student Review #2 Student Review #3 Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now. GMAT/MBA Expert GMAT Instructor Joined 09 Oct 2010 Posted: 1449 messages Followed by: 32 members Upvotes: 59 BTGmoderatorLU wrote: Source: Economist GMAT Tom drives from town A to town B, driving at a constant speed of 60 miles per hour. From town, B Tom immediately continues to town C. The distance between A and B is twice the distance between B and C. If the average speed of the whole journey was 36 mph, then what is Tom's speed driving from B to C in miles per hour? A. 12 B. 20 C. 24 D. 30 E. 36 $$?\,\, = \,\,\,{V_{B \to C}}\,\,\,\,\,\,\left[ {\,{\rm{mph}}\,} \right]$$ LetÂ´s use UNITS CONTROL, one of the most powerful tools of our method! $${\rm{Let}}\,\,B \to C = 180\,\,{\rm{miles}}\,\,\,\,\,\left[ {\,180 = LCM\left( {60,36} \right)\,} \right]$$ $$\left. \matrix{ \left. {\matrix{ {A \to B} \cr {2 \cdot 180\,\,{\rm{miles}}\,\,} \cr } } \right\}\,\,\,\,\,\,\,2 \cdot 180\,\,{\rm{miles}}\,\,\, \cdot \,\,\,\left( {{{1\,\,{\rm{h}}} \over {60\,\,{\rm{miles}}}}} \right)\,\,\,\, = \,\,\,\,6\,\,\,{\rm{h}}\,\,\, \hfill \cr \left. {\matrix{ {B \to C} \cr {180\,\,{\rm{miles}}\,\,} \cr } } \right\}\,\,\,\,\,\,\,180\,\,{\rm{miles}}\,\,\, \cdot \,\,\,\left( {{{1\,\,{\rm{h}}} \over {{V_{B \to C}}\,\,{\rm{miles}}}}} \right)\,\,\,\, = \,\,\,\,{{180} \over {{V_{B \to C}}}}\,\,\,{\rm{h}}\,\,\,\,\, \hfill \cr \left. {\matrix{ {A \to C} \cr {3 \cdot 180\,\,{\rm{miles}}\,\,} \cr } } \right\}\,\,\,\,\,\,\,3 \cdot 180\,\,{\rm{miles}}\,\,\, \cdot \,\,\,\left( {{{1\,\,{\rm{h}}} \over {36\,\,{\rm{miles}}}}} \right)\,\,\,\, = \,\,\,\,15\,\,\,{\rm{h}} \hfill \cr} \right\}\,\,\,\,\,\, \Rightarrow \,\,\,\,\,6 + {{180} \over {{V_{B \to C}}}} = 15\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,{{180} \over {{V_{B \to C}}}} = 9\,\,\,\,\,\, \Rightarrow \,\,\,\,\,?\,\, = \,\,{V_{B \to C}} = 20\,\,\,\,\,\,\,\left[ {\rm{h}} \right]$$ 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 GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2852 messages Followed by: 18 members Upvotes: 43 BTGmoderatorLU wrote: Source: Economist GMAT Tom drives from town A to town B, driving at a constant speed of 60 miles per hour. From town, B Tom immediately continues to town C. The distance between A and B is twice the distance between B and C. If the average speed of the whole journey was 36 mph, then what is Tom's speed driving from B to C in miles per hour? A. 12 B. 20 C. 24 D. 30 E. 36 We can let the distance between B and C = d, and thus the distance between A and B = 2d. We can let r = Tom's speed driving from B to C, in miles per hour, and create the equation: (2d + d)/(2d/60 + d/r) = 36 3d/(d/30 + d/r) = 36 3d = 36d/30 + 36d/r 3 = 6/5 + 36/r Multiplying both sides of the equation by 5r, we have: 15r = 6r + 180 9r = 180 r = 20 Answer: B _________________ 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 • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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