A car starts from X and moves towards Y. At the same time : Problem Solving (PS)

My Profile Logout

Test's Subscription Expires:

My Follow Feed Kudos My Error Log

Messages and Replies

Settings Mark All Read

See All

Applicant Notifications

Settings Mark All Read

See All

Global notifications

Settings Mark All Read

See All

A car starts from X and moves towards Y. At the same time

Sort by Date

Sort by Kudos

Author

Message

TAGS:

Hide Tags

Director

Joined: 17 Dec 2012

Posts: 629

Location: India

A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

29 Aug 2013, 03:15

00:00

Difficulty:

25% (medium)

Question Stats:

78% (02:08) correct

22% (02:04) wrong

based on 283 sessions

HideShow timer Statistics

A car starts from X and moves towards Y. At the same time another car starts from Y and moves towards X. Both travel at a constant speed and meet after 4 hours. During that time, the faster car traveled 2/3 of the distance XY. How long would it take the slower car to travel the distance XY?

A 6 hours
B. 8 hours
C. 10 hours
D. 12 hours
E. 15 hours

Spoiler: OA

_________________

Srinivasan Vaidyaraman
Sravna Holistic Solutions
http://www.sravnatestprep.com

Holistic and Systematic Approach

Intern

Joined: 01 Oct 2013

Posts: 4

WE: Manufacturing and Production (Manufacturing)

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

07 Oct 2013, 01:32

Ans is D
This is how
Say Total Dist. XY = 1
Let constant rate of Car X & Car Y be "x" & "y" respectively
Car X distance traveled = 2/3
Time = 4 hrs
Rate of Car X=2/3 div by 4
i.e x = 1/6

When traveling towards each other
Speed = Dist./Time
(x+y) = 1/4
substituting fr "x" in above eqn. we get
y = 1/12
Therefore Time taken to travel Distance XY = 1 div. 1/12
Ans D) 12

Intern

Joined: 12 Sep 2012

Posts: 2

Location: Spain

GPA: 3.95

WE: General Management (Retail)

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

07 Oct 2013, 03:56

My view on this Question:

If one car travelled 2/3, then the other car must have travelled only 1/3, as they are meeting after 4 hours in a certain point. So:

(1/3)XY= 4*y --> It took the car 4 hours to travel 1/3 of the distance at a constant speed y.

So if we solve this last equation:

XY= 3*4*y= 12*y --> It will take this car 12 hours in total to reach its final destination.

Answer: D

Intern

Joined: 21 Sep 2011

Posts: 10

Concentration: General Management

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

09 Oct 2013, 00:33

SravnaTestPrep wrote:

D --> Take a smart number (as X travel's 2/3 & Y travel's 1/3 of the distance, i took D = 60 since ,we also have to divide 2/3 & 1/3 by 4 i.e time taken by both car)
D = 60 , therefore , X travels 60*2/3 = 40. Now, since t = 4 , therefore X's speed = 40/4 = 10.
Similarly , Y travels 60*1/3 = 20. Since t=4 , Y's Speed = 20/4 = 5
Therefore total time taken by Y is t = D/S = 60/5 = 12hrs

Intern

Joined: 26 Feb 2012

Posts: 14

Concentration: Strategy, International Business

Schools: INSEAD Jan '16

GMAT 3: 640 Q49 V29

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

09 Oct 2013, 07:51

SravnaTestPrep wrote:

Quick and easy:
It is clear that the slower car is the one starting from Y (car B).
If car B spends 4h to complete d/3 of the traject, then it will spend 8h to complete 2d/3 and 12h to make the whole traject (3d/3).

Answer is D, 12h.

Intern

Joined: 14 Dec 2011

Posts: 16

Location: India

Concentration: Technology, Nonprofit

GMAT 1: 640 Q48 V29

GMAT 2: 660 Q45 V35

GPA: 3.5

WE: Information Technology (Computer Software)

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

12 Oct 2013, 01:57

SravnaTestPrep wrote:

Take XY = 60 km
Car A travelled distance D1 = 2/3*60 = 40km
Car B travelled distance D2 = 1/3*60 = 20km

Car B is slower, travelling 20 km in 4 hours. Car B speed = 20/4 = 5 km/h

Time for Car B to travel whole distance XY = 60 km:
D = S*T
60 = 5*T
T = 60/5 = 12 hours - Answer.

Hope it helps.

Joined: 02 Jul 2012

Posts: 1176

Location: India

Concentration: Strategy

Schools: Ross '16 (D), McCombs '16 (D), Tepper '16 (D), Kenan-Flagler '16 (WA), Olin '16 (M$)

GMAT 1: 740 Q49 V42

GPA: 3.8

WE: Engineering (Energy and Utilities)

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

12 Oct 2013, 03:37

The faster car travels $\frac{2}{3}$ of this distance in 4 hours.

The slower car hence travels $\frac{1}{3}$ of this distance in 4 hours.

So, to travel the total distance , the slower car would take 4*3 = 12 hours

Answer is D
_________________

Did you find this post helpful?... Please let me know through the Kudos button.

Thanks To The Almighty - My GMAT Debrief

GMAT Reading Comprehension: 7 Most Common Passage Types

Manager

Joined: 13 Aug 2012

Posts: 95

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

15 Oct 2013, 00:43

Distance is in the ratio of 2:1 so speed will also be 2:1. Time will be in the ratio of 1:2 because Speed is inversely proportional to time keeping distant constant.
The slowest car's time is $\frac{1}{3}$
so $\frac{1}{3}*x=4$
$x=12$

SVP

Joined: 06 Sep 2013

Posts: 1720

Concentration: Finance

Schools: HBS '17 (WA$), Wharton '17 (A)

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

09 Jan 2014, 11:56

SravnaTestPrep wrote:

4 (x+y) = d

4x = 2/3d

4y = 1/3d

Therefore, y = d/12

D 12 hours

Manager

Joined: 26 Feb 2012

Posts: 100

Location: India

Concentration: General Management, Finance

WE: Engineering (Telecommunications)

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

16 Feb 2014, 07:34

Lets solve it "plug value" ,method as it about fraction....
Say total distance 3 miles so faster car traveled 2 mile and slower one is 1 mile..

So the slower one traveled 1 mile in 4 hour(because they met in 4 hours) that makes the rate 1/4...
Now lets assume T hour required to cover the distance so 1/4*T=3 So T=12 hours(d) ..ans...

Rgds
Prasannajeet

Director

Joined: 19 Oct 2013

Posts: 509

Location: Kuwait

GPA: 3.2

WE: Engineering (Real Estate)

Re: A car starts from X and moves towards Y. At the same time [#permalink]

Show Tags

07 Sep 2018, 17:01

If we let the distance = 12

Then the faster car have travelled 8 miles $= \frac{2}{3}* 12 = 8$ miles. As a result the slower car have travelled 4 miles.

Since they meet in 4 hours, then Speed of the slow car $= \frac{4}{4} = 1$.

On the basis of our assumption that Distance = 12 then Time would be $= \frac{12}{1} = 12$ hours