NEW HERE? LEARN MORE
closeclose
Last visit was: 25 Apr 2024, 19:22 It is currently 25 Apr 2024, 19:22
Decision Tracker
My Rewards
New posts
New comers' posts

Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

My girlfriend leaves Berlin with destination Hamburg at the

User avatar
allabout
Manager
Manager
Joined: 17 Dec 2005
Posts: 232
Own Kudos [?]: 74 [0]
Given Kudos: 0
Location: Germany
Send PM
My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 03:14
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Hide Show timer Statistics
My girlfriend leaves Berlin with destination Hamburg at the same time I leave Hamburg with destination Berlin and our trains are driving a parallel track with the same length. After our trains pass each other at time X my girlfriend takes 1 hour to reach Hamburg with a train driving 240 km/h and I need 4 hours to reach Berlin. How fast is my train driving?



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
User avatar
mand-y
Manager
Manager
Joined: 05 Oct 2005
Posts: 134
Own Kudos [?]: 33 [0]
Given Kudos: 0
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 10:59
interesting exercise! any OA

My trial

240(X+1)/X+4


IF i am correct I will explain
avatar
thearch
Manager
Manager
Joined: 19 Feb 2005
Posts: 212
Own Kudos [?]: 69 [0]
Given Kudos: 0
Location: Milan Italy
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 11:16
I actually found a number, 120 km/h, calculations are lengthy though
so I suspect of my answer...
User avatar
allabout
Manager
Manager
Joined: 17 Dec 2005
Posts: 232
Own Kudos [?]: 74 [0]
Given Kudos: 0
Location: Germany
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 12:03
Actually the solution is a number, the X is just for confusion :wink:
User avatar
allabout
Manager
Manager
Joined: 17 Dec 2005
Posts: 232
Own Kudos [?]: 74 [0]
Given Kudos: 0
Location: Germany
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 12:42
I case your your calcualtion takes too long, use the following:

g= girlfriend
m= me


Speed of g / speed of m = sqrt(time taken by m after passing X) / sqrt( time taken by g after passing X)

= sqrt(4) / sqrt(1)

= 2/1

So "g" is twice as fast as "m"

m= 120 km/h
User avatar
Riuscita
Manager
Manager
Joined: 10 Jan 2006
Posts: 83
Own Kudos [?]: 30 [0]
Given Kudos: 0
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 14:25
allabout, Can you please explain the formula used??

Thanks
User avatar
ps_dahiya
VP
VP
Joined: 20 Nov 2005
Posts: 1490
Own Kudos [?]: 1133 [0]
Given Kudos: 0
Concentration: Strategy, Entrepreneurship
Schools:Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
 Q50  V34
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 15:30
B|-------x km ---------------|-------240 km----------| H

Speed of Girl's train = 240 km/h that of boy = y

Then 240/x = x/240 i.e x*y = 240 * 240

and x/4 = y

Solve these two equations for y, we get y = 120
User avatar
vipin7um
Manager
Manager
Joined: 08 Sep 2004
Posts: 96
Own Kudos [?]: 105 [0]
Given Kudos: 0
Location: New York City, USA
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   26 Jan 2006, 15:51
I think its a pretty straightforward problem. GF takes 1 hr to reach H and BF takes 4 hrs to reach B. So speed of BF's train is 1/4th of speed of GF's train. => the speed of BF's train is 240/4 = 60 km/h.

- Vipin
User avatar
allabout
Manager
Manager
Joined: 17 Dec 2005
Posts: 232
Own Kudos [?]: 74 [0]
Given Kudos: 0
Location: Germany
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   27 Jan 2006, 01:40
Riuscita wrote:
allabout, Can you please explain the formula used??

Thanks


Why exactly sqrt of the respective times, don't know. But here's another fast way, if you feel reluctant with the formula.

1) the ratio of the respective speeds is X+4 : X+1 or 1 : X+1/X+4

2) g has made 240*X km's at time X; m takes 4 hours to cover the distance already traveled by g: 240X/4

So the ratio of speed and distance is

240 : 240X/4 : 1 : X+1/X+4, or, because you have to make the units equally

1 : X/4 : 1 : X+1/X+4

So,

X/4=X+1/X+4

Solve for X

X² + 4X = 4X + 4

X = +- 2, -2 is out because there is no negative time

Plug in

240*2/4=120
User avatar
mbadownunder
Intern
Intern
Joined: 04 Jan 2006
Posts: 22
Own Kudos [?]: 2 [0]
Given Kudos: 0
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   27 Jan 2006, 03:35
[quote="ps_dahiya"]B|-------x km ---------------|-------240 km----------| H

Speed of Girl's train = 240 km/h that of boy = y

Then 240/x = x/240 i.e x*y = 240 * 240

and x/4 = y

Solve these two equations for y, we get y = 120[/quote]

Hey PS how do you get 240/x = y/240 and x/4 = y??

I am still stuck at 240(x+1)/x+4

The way I worked it is

total distance travelled by Girlfriend = 240x+240
total distance travelled by guy = xy+4y
I then solved for y. I dont get 120 though
User avatar
ipc302
Manager
Manager
Joined: 13 Dec 2005
Posts: 103
Own Kudos [?]: 12 [0]
Given Kudos: 0
Location: Milwaukee,WI
Send PM
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink] New post   27 Jan 2006, 08:54
Say the distance between the 2 station is Y

speed of girl's train 240
speed of boy's train S

relative speed of approach is 240 +S

since they cross after X hour so they travelled Y distance in total

so distance =speed * time
Y = (240 +S) * X ----- equation 1

also for girl distance =speed * time
Y = 240 * (x+1) ------ equation 2

for boy distance = speed * time
Y = S * (x+4) ----- equation 3


solve all the above 3 equation and u will get the answer
S =120 km/hrs
x = 2hrs
Y = 720 km



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
GMAT Club Bot
gmatclubot
Re: My girlfriend leaves Berlin with destination Hamburg at the [#permalink]
27 Jan 2006, 08:54
Moderators:
Bunuel
Math Expert
92915 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions