• 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 time it took car A to travel 400 miles was 2 hours less tagged by: swerve ##### This topic has 2 expert replies and 0 member replies ### Top Member ## The time it took car A to travel 400 miles was 2 hours less ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult The time it took car A to travel 400 miles was 2 hours less than the time it took car B to travel the same distance. If car A's average speed was 10 miles per hour greater than that of car B, what was car B's average speed in miles per hour? A. 20 B. 30 C. 40 D. 50 E. 80 The OA is C Source: GMAT Paper Tests ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 10129 messages Followed by: 494 members Upvotes: 2867 GMAT Score: 800 Top Reply Hi swerve, We're told that the time it took car A to travel 400 miles was 2 hours LESS than the time it took car B to travel the same distance and car A's average speed was 10 miles per hour GREATER than that of car B. We're asked for car B's average speed in miles per hour. This question can be approached in a couple of different ways. Since it's essentially about basic arithmetic (re: two 'pairs' of numbers that have a product of 400), you would likely find it fastest to TEST THE ANSWERS. To start, the difference in the time that the two cars traveled is exactly 2 hours and we know that Car B was going exactly 10 mph slower than Car A. Based on the prompt and the answer choices, we're clearly dealing with nice 'round' numbers, so let's start with an answer that divides evenly into 400... Let's TEST Answer C: 40 miles/hour IF.... Car B is traveling 40 mph, then it takes 400/40 = 10 hours to complete that drive. We're told that Car A's speed is 10 mph greater than Car B's speed, so.... Car A is traveling 50 mph... and that would take 400/50 = 8 hours to complete that drive. Here, the difference in travel time is exactly 2 hours - and this matches what we were told - so this MUST be the answer. Final Answer: C 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: 2424 messages Followed by: 18 members Upvotes: 43 swerve wrote: The time it took car A to travel 400 miles was 2 hours less than the time it took car B to travel the same distance. If car A's average speed was 10 miles per hour greater than that of car B, what was car B's average speed in miles per hour? A. 20 B. 30 C. 40 D. 50 E. 80 The OA is C Source: GMAT Paper Tests We are given that cars A and B both traveled 400 miles and that car Aâ€™s average speed was 10 mph greater than that of car B. We can let the rate of car B = r and the rate of car A = r + 10. Since both cars traveled 400 miles and time = distance/rate, the time of car A is 400/(r+10). We are also given that it took car A 2 hours less than it took car B to travel the 400 miles. We can set up the following equation: 400/(r+10) + 2 = 400/r Multiplying the entire equation by r(r+10), we have: 400r + 2(r)(r+10) = 400(r+10) 400r + 2r^2 + 20r = 400r + 4000 2r^2 + 20r - 4000 = 0 r^2 + 10r - 2000 = 0 (r + 50)(r - 40) = 0 r = -50 or r = 40 Since r must be positive, then r = 40. Answer: C _________________ 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 • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE 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 • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder 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 Practice Test & Review How would you score if you took the GMAT 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 GMAT Exam Know how you'd score today for$0

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

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

### Top First Responders*

1 Jay@ManhattanReview 68 first replies
2 Brent@GMATPrepNow 65 first replies
3 GMATGuruNY 41 first replies
4 Ian Stewart 23 first replies
5 Scott@TargetTestPrep 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

200 posts
2 Brent@GMATPrepNow

GMAT Prep Now Teacher

91 posts
3 Max@Math Revolution

Math Revolution

85 posts
4 Jay@ManhattanReview

Manhattan Review

73 posts
5 GMATGuruNY

The Princeton Review Teacher

65 posts
See More Top Beat The GMAT Experts