• 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 ## Cars emerging from a motorway arrive at a junction that tagged by: BTGmoderatorLU ##### This topic has 1 expert reply and 1 member reply ### Top Member ## Cars emerging from a motorway arrive at a junction that ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Source: Economist GMAT Cars emerging from a motorway arrive at a junction that splits the road into two separate lanes. The number of cars per hour that continue in either lane is constant. If 700 cars per hour were diverted from the left lane to the right lane, the number of cars entering the right lane per hour would be twice as big as the number of cars entering the left lane per hour. Alternatively, if 700 cars per hour were diverted from the right lane to the left lane, the number of cars entering the left lane per hour would be four times as great as the number of cars entering the right lane per hour. How many cars enter the left lane per hour? A. 1300 B. 1500 C. 1700 D. 1900 E. 2100 The OA is C ### Top Member Legendary Member Joined 02 Mar 2018 Posted: 1121 messages Followed by: 2 members Let represent the right lane with 'x' and the left lane with 'y'. No of cars per hour is constant. For right lane, $$x+700=2\left(y-700\right)\ \ \ \ \ \ -----\ eqn\ i$$ For left lane, $$y+700=4\left(x-700\right)\ \ \ \ \ \ -----\ eqn\ ii$$ $$From\ i,\ x+700=2y-1400$$ $$x=2y-1400-700$$ $$x=2y-2100\ \ \ \ \ -----\ eqn\ iii$$ Let's find Y (i.e the number of car entering). $$from\ ii,\ y+700=4x-2800$$ substitute value for x derived in eqn iii $$Therefore,\ y+700=4\left(2y-2100\right)-2800$$ $$y+700=8y-8400-2800$$ $$y=8y-8400-2800-700$$ $$-7y=-11900$$ Divide both side by 7 $$Then,\ y=1700$$ ### 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 Cars emerging from a motorway arrive at a junction that splits the road into two separate lanes. The number of cars per hour that continue in either lane is constant. If 700 cars per hour were diverted from the left lane to the right lane, the number of cars entering the right lane per hour would be twice as big as the number of cars entering the left lane per hour. Alternatively, if 700 cars per hour were diverted from the right lane to the left lane, the number of cars entering the left lane per hour would be four times as great as the number of cars entering the right lane per hour. How many cars enter the left lane per hour? A. 1300 B. 1500 C. 1700 D. 1900 E. 2100 We can PLUG IN THE ANSWERS, which represent the number of cars in the left lane. Answer choice C: 1700 If 700 cars per hour were diverted from the left lane to the right lane, the number of cars entering the right lane per hour would be twice as big as the number of cars entering the left lane per hour. After 700 cars are diverted, the number of cars entering the left lane = 1700-700 = 1000. Since the number of cars entering the right lane is twice the number entering the left lane, the number of cars entering the right lane = 2*1000 = 2000. Thus, prior to the diversion of the 700 cars, the number of cars in the right lane = 1000-700 = 1300. If 700 cars per hour were diverted from the right lane to the left lane, the number of cars entering the left lane per hour would be four times as great as the number of cars entering the right lane per hour. After 700 cars are diverted, the number of cars entering the right lane = 1300-700 = 600 and the number of cars entering the left lane = 1700+700 = 2400. Left lane/right lane = 2400/600 = 4. Success! The number of cars entering the left lane is 4 times as great as the number of cars entering the right lane. The correct answer is C. _________________ 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. • FREE GMAT Exam Know how you'd score today for$0

Available with Beat the GMAT members only code

• Free Trial & Practice Exam
BEAT THE GMAT EXCLUSIVE

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 Veritas GMAT Class
Experience Lesson 1 Live Free

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• 5 Day FREE Trial
Study Smarter, Not Harder

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

• Get 300+ Practice Questions

Available with Beat the GMAT members only code

• Award-winning private GMAT tutoring
Register now and save up to \$200

Available with Beat the GMAT members only code

• Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

### Top First Responders*

1 Brent@GMATPrepNow 43 first replies
2 Ian Stewart 35 first replies
3 Jay@ManhattanReview 32 first replies
4 GMATGuruNY 27 first replies
5 Scott@TargetTestPrep 13 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

189 posts
2 Max@Math Revolution

Math Revolution

90 posts
3 Brent@GMATPrepNow

GMAT Prep Now Teacher

75 posts
4 GMATGuruNY

The Princeton Review Teacher

44 posts
5 Ian Stewart

GMATiX Teacher

42 posts
See More Top Beat The GMAT Experts