BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Trains crashing

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Senior | Next Rank: 100 Posts
Posts: 58
Joined: Thu Jul 22, 2010 5:40 pm
Thanked: 1 times

Trains crashing

by Jinglander » Tue Aug 10, 2010 8:10 pm
It takes the high-speed train x hours to travel the z miles from Town A to Town B at a constant rate, while it takes the regular train y hours to travel the same distance at a constant rate. If the high-speed train leaves Town A for Town B at the same time that the regular train leaves Town B for Town A, how many more miles will the high-speed train have traveled than the regular train when the two trains pass each other?

correct answer is



z(y - x) /

x + y
Top
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 1179
Joined: Sun Apr 11, 2010 9:07 pm
Location: Milpitas, CA
Thanked: 447 times
Followed by:88 members

by Rahul@gurome » Tue Aug 10, 2010 8:21 pm
Jinglander wrote:It takes the high-speed train x hours to travel the z miles from Town A to Town B at a constant rate, while it takes the regular train y hours to travel the same distance at a constant rate. If the high-speed train leaves Town A for Town B at the same time that the regular train leaves Town B for Town A, how many more miles will the high-speed train have traveled than the regular train when the two trains pass each other?
Speed of high speed train = z/x mph
Speed of regular train = z/y mph
Relative speed of the 2 trains = z/x + z/y
Time that will be taken for the trains to meet = z/(z/x + z/y) = z/{z(x+y)/xy)} = xy/(x + y)

Distance traveled by high speed train in time xy/(x + y) = Speed * Time = z/x * xy/(x + y) = zy/(x + y)
Distance traveled by regular train in time xy/(x + y) = Speed * Time = z/y * xy/(x + y) = zx/(x + y)

Difference between the distances = zy/(x + y) - zx/(x + y) = z(y - x)/ (x +y)
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Top
Post new topic Post Reply
• Page 1 of 1