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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 ## A certain road trip was completed in two parts... tagged by: swerve ##### This topic has 3 expert replies and 0 member replies ### Top Member ## A certain road trip was completed in two parts... A certain road trip was completed in two parts interrupted by an hour-long lunch break. During the first portion of the trip, the average speed was 55 miles per hour and the average speed during the second part of the trip was 63 miles per hour. If the trip was 480 miles long and took a total of 8 hours (excluding the time stopped for lunch) then which of the following is the amount of time spent driving before the lunch break? A. 2 B. 3 C. 4 D. 5 E. 6 The OA is B. I don't have clear this PS question. I appreciate if any expert explains it to me. Thank you so much. ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12442 messages Followed by: 1244 members Upvotes: 5254 GMAT Score: 770 swerve wrote: A certain road trip was completed in two parts interrupted by an hour-long lunch break. During the first portion of the trip, the average speed was 55 miles per hour and the average speed during the second part of the trip was 63 miles per hour. If the trip was 480 miles long and took a total of 8 hours (excluding the time stopped for lunch) then which of the following is the amount of time spent driving before the lunch break? A. 2 B. 3 C. 4 D. 5 E. 6 Let's start with a word equation (distance traveled during FIRST part of trip) + (distance traveled during SECOND part of trip) = 480 miles Let t = time spend on FIRST part of trip (in hours) So, 8-t = time spend on SECOND part of trip (since the ENTIRE driving time was 8 hour) Distance = (speed)(time) So, we can write: (55)(t ) + (63)(8 - t) = 480 Expand: 55t + (504 - 63t) = 480 Simplify: -8t + 504 = 480 Subtract 504 from both sides: -8t = -24 Solve: t = 3 Answer: B Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use our video course along with Sign up for our free Question of the Day emails And check out all of our free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 9955 messages Followed by: 493 members Upvotes: 2867 GMAT Score: 800 Hi swerve, We're told that a certain road trip was completed in two parts interrupted by an hour-long lunch break. During the first portion of the trip, the average speed was 55 miles per hour and the average speed during the second part of the trip was 63 miles per hour. We're also told the trip was 480 miles long and took a total of 8 hours (excluding the time stopped for lunch). We're asked for the number of hours spent driving BEFORE the lunch break. This question can be solved in a number of different ways; here's how you can TEST THE ANSWERS. To start, since the trip was 480 miles and took 8 hours of drive time, the average speed for the trip was 480/8 = 60 miles/hour. With the two given speeds (55 mph and 63 mph) - and since 63 is closer to 60 than 55 is to 60 - we will need to speed MORE time at 63 mph than we do at 55 mph to end up with an average speed of 60 mph. Thus, the correct answer has to be LESS than 4 hours. Eliminate Answers C, D and E. Let's TEST Answer B: 3 hours IF... we spent 3 hours at 55 miles per hour, then we travel (3)(55) = 165 miles we then spend 5 hours at 63 miles per hour, so we travel (5)(63) = 315 miles 165 miles + 315 miles = 480 miles This is an exact match for 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 09 Apr 2015 Posted: 1461 messages Followed by: 17 members Upvotes: 39 swerve wrote: A certain road trip was completed in two parts interrupted by an hour-long lunch break. During the first portion of the trip, the average speed was 55 miles per hour and the average speed during the second part of the trip was 63 miles per hour. If the trip was 480 miles long and took a total of 8 hours (excluding the time stopped for lunch) then which of the following is the amount of time spent driving before the lunch break? A. 2 B. 3 C. 4 D. 5 E. 6 We are given that the average speed before lunch was 55 mph. If we let t equal the time spent traveling before lunch, the distance covered is 55t. Since the trip takes 8 hours, excluding the lunch break, the second part of the trip takes (8 - t) hours, and the distance covered in this part is 63(8 - t). Since the sum of the distances in the first and second parts must equal the total length of the trip, which is 480 miles, we can create the following equation and determine t: 55t + 63(8 - t) = 480 55t + 504 - 63t = 480 24 = 8t t = 3 Answer: B _________________ Jeffrey Miller Head of GMAT Instruction • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

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