• 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 ## Carlos runs a lap around the track in x seconds. His second tagged by: BTGmoderatorLU ##### This topic has 4 expert replies and 0 member replies ### Top Member ## Carlos runs a lap around the track in x seconds. His second ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Source: Manhattan Prep Carlos runs a lap around the track in x seconds. His second lap is five seconds slower than the first lap, but the third lap is two seconds faster than the first lap. What is Carlosâ€™s average (arithmetic mean) number of minutes per lap, in terms of x? $$A.\ x-1$$ $$B.\ x+1$$ $$C.\ \frac{x-1}{60}$$ $$D.\ \frac{x+1}{60}$$ $$E.\ \frac{x+3}{60}$$ The OA is D ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15348 messages Followed by: 1864 members Upvotes: 13060 GMAT Score: 790 BTGmoderatorLU wrote: Source: Manhattan Prep Carlos runs a lap around the track in x seconds. His second lap is five seconds slower than the first lap, but the third lap is two seconds faster than the first lap. What is Carlosâ€™s average (arithmetic mean) number of minutes per lap, in terms of x? $$A.\ x-1$$ $$B.\ x+1$$ $$C.\ \frac{x-1}{60}$$ $$D.\ \frac{x+1}{60}$$ $$E.\ \frac{x+3}{60}$$ Let x = 5 seconds for the first lap, implying 10 seconds for the second lap, 3 seconds for the third lap, and a total of 18 seconds for all 3 laps. (18 seconds)/(3 laps) = (6 seconds)/(1 lap) = 1/10 minute per lap. The correct answer must yield a value of 1/10 when x=5. Only D works: (x+1)/60 = (5+1)/60 = 6/60 = 1/10. The correct answer is D. _________________ 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 Elite Legendary Member Joined 23 Jun 2013 Posted: 10197 messages Followed by: 496 members Upvotes: 2867 GMAT Score: 800 Hi All, We're told that Carlos runs a lap around the track in X SECONDS. His second lap is five SECONDS SLOWER than the first lap, but the third lap is two SECONDS FASTER than the first lap. We're asked for Carlosâ€™s average (arithmetic mean) number of MINUTES per LAP, in terms of X. This question can be solved rather easily by TESTing VALUES (as Mitch has shown). It can also be solved Algebraically, although you have to make sure to do the extra 'step' of converting seconds to minutes. To start, we know that the 3 times/lap are : X seconds, (X + 5) seconds and (X - 2) seconds, so the AVERAGE time per lap (in seconds) is: (X + X + 5 + X - 2)/3 = (3X + 3)/3 = (X + 1) seconds Since 1 minute = 60 seconds, to convert an answer "in seconds" to an answer "in minutes", we need to divide by 60... (X + 1)/60 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 09 Oct 2010 Posted: 1449 messages Followed by: 32 members Upvotes: 59 BTGmoderatorLU wrote: Source: Manhattan Prep Carlos runs a lap around the track in x seconds. His second lap is five seconds slower than the first lap, but the third lap is two seconds faster than the first lap. What is Carlosâ€™s average (arithmetic mean) number of minutes per lap, in terms of x? $$A.\ x-1\,\,\,\,\,\,\,B.\ x+1\,\,\,\,\,\,\,C.\ \frac{x-1}{60}\,\,\,\,\,\,\,D.\ \frac{x+1}{60}\,\,\,\,\,\,\,E.\ \frac{x+3}{60}$$ $$?\,\,\,:\,\,\,\,\,\,f\left( x \right)\,\,\,{{\min } \over {{\rm{lap}}}}$$ \eqalign{ & {1^{{\rm{st}}}}\,{\rm{lap}}\,\,\,\, \to \,\,\,\,\,\,\,x\,\,\sec \cr & {2^{{\rm{nd}}}}\,{\rm{lap}}\,\,\,\, \to \,\,\,\,\,\left( {x + 5} \right)\,\,\sec \,\,\,\,\, \cr & {3^{{\rm{rd}}}}\,{\rm{lap}}\,\,\,\, \to \,\,\,\,\,\left( {x - 2} \right)\,\,\sec \,\, \cr} LetÂ´s use UNITS CONTROL, one of the most powerful tools of our method! $?\,\,\, = \,\,\,\,\frac{{\left( {3x + 3} \right)\,\,\sec }}{{3\,\,{\text{laps}}\,}}\,\,\,\left( {\frac{{1\,\,\min }}{{60\,\,\sec }}} \right)\,\,\,\, = \,\,\,\,\frac{{x + 1}}{{60}}\,\,\,\,\frac{{\min }}{{{\text{lap}}}}$ 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: 2791 messages Followed by: 18 members Upvotes: 43 BTGmoderatorLU wrote: Source: Manhattan Prep Carlos runs a lap around the track in x seconds. His second lap is five seconds slower than the first lap, but the third lap is two seconds faster than the first lap. What is Carlosâ€™s average (arithmetic mean) number of minutes per lap, in terms of x? $$A.\ x-1$$ $$B.\ x+1$$ $$C.\ \frac{x-1}{60}$$ $$D.\ \frac{x+1}{60}$$ $$E.\ \frac{x+3}{60}$$ The total number of seconds it takes Carlos to run the 3 laps is x + (x + 5) + (x - 2) = 3x + 3. So the number of seconds per lap is (3x + 3)/3 = x + 1, and hence, the number of minutes per lap is (x + 1)/60. 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 • Award-winning private GMAT tutoring Register now and save up to200

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

• Get 300+ Practice Questions

Available with Beat the GMAT members only code

• Magoosh
Study with Magoosh GMAT prep

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

• 5 Day FREE Trial
Study Smarter, Not Harder

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

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

• 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

### Top First Responders*

1 Ian Stewart 57 first replies
2 Brent@GMATPrepNow 31 first replies
3 Jay@ManhattanReview 29 first replies
4 GMATGuruNY 21 first replies
5 ceilidh.erickson 15 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

199 posts
2 Max@Math Revolution

Math Revolution

84 posts
3 Brent@GMATPrepNow

GMAT Prep Now Teacher

69 posts
4 Ian Stewart

GMATiX Teacher

65 posts
5 GMATGuruNY

The Princeton Review Teacher

40 posts
See More Top Beat The GMAT Experts