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

Redeem

distance speed time

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 222
Joined: Mon Oct 13, 2008 4:04 pm
Thanked: 3 times
Followed by:2 members

distance speed time

by venmic » Mon Sep 05, 2011 12:11 pm
Two trains continuously travel between Washington D.C. and Baltimore which are 120 miles apart. The trains start simultaneously, with train A starting in Washington DC and train B starting in Baltimore, and travel at 30 and 90 mph respectively. If the station turnaround times are negligible, what is the distance between the point where the trains meet for the first time and the point where they meet for the second time?

30

please suggest
Top
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 158
Joined: Sat Sep 03, 2011 10:31 am
Thanked: 29 times
Followed by:2 members

by gmatclubmember » Mon Sep 05, 2011 1:03 pm
First time: 30 miles from DC and second time 60 miles from DC
Top
Master | Next Rank: 500 Posts
Posts: 222
Joined: Mon Oct 13, 2008 4:04 pm
Thanked: 3 times
Followed by:2 members

by venmic » Mon Sep 05, 2011 1:12 pm
can someone give me a detailed explanation

Thanks
Top
Junior | Next Rank: 30 Posts
Posts: 12
Joined: Tue Aug 30, 2011 7:55 pm
Thanked: 1 times

by jbivins » Mon Sep 05, 2011 1:23 pm
So imagine a line with point A--------------------B and will say the distance between them 120 miles. We will assume Ad=0 miles and Bd=120 miles.
imagine the 90 mph trains leave point B at t=0 and the 30 mile per hour train leaves point A at t=0

so at t=1 hour A is at the 30 mile marker and B is also at the 30 mile marker. (120 miles-90 mph(1hour))=30. so 30 is the first meeting point.

Now well assume they keep traveling for another hour

Now A is at the 60 mile marker (30 miles +30 mph(1hour))=60 miles
And B travels 90 miles in an hour, but after 30 miles it hits point A and has to turn back around and continue 60 more miles. So it is also at the 60 mile marker with A therefore 60 is the second meeting point

So 60 miles -30 miles=30 miles

I hope this helps
Top
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Mon Aug 15, 2011 11:08 am

by prasad433 » Wed Sep 07, 2011 6:10 am
venmic wrote:can someone give me a detailed explanation

Thanks

in this questions .. first observe the speeds 30mph and 90mph means.. in one hour they both cover a distance of 120 miles(which is the distance bwtenn dc and balti) travelling in oppo directions.so DC trains(30mph) travels 30 miles in 1 hrs and in the same hr Baltimore trains covers remaining 90 miles ... so this is where they meet for the first time.which is 30 miles from DC and 90 miles from balti.
Top
Post new topic Post Reply
• Page 1 of 1