Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 23 May 2017, 23:14

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

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Two trains, Q and P, are traveling on straight and parallel

Author Message
TAGS:

Hide Tags

Intern
Joined: 27 Sep 2009
Posts: 41
Followers: 0

Kudos [?]: 85 [0], given: 4

Two trains, Q and P, are traveling on straight and parallel [#permalink]

Show Tags

23 May 2010, 09:24
00:00

Difficulty:

15% (low)

Question Stats:

78% (01:49) correct 22% (01:17) wrong based on 96 sessions

HideShow timer Statistics

Two trains, Q and P, are traveling on straight and parallel tracks. Q and P are traveling at different constant rates. If train Q is now 3 miles ahead of train P, in how many minutes will train Q be 6 miles ahead of train P ?

(1) Train Q is traveling at a speed of 150 mph and train P is traveling at a speed of 120 mph.

(2) Four minutes ago, train Q was 1 mile ahead of train P.
[Reveal] Spoiler: OA
Senior Manager
Affiliations: SPG
Joined: 15 Nov 2006
Posts: 327
Followers: 16

Kudos [?]: 747 [0], given: 28

Re: Data sufficiency - 600 level question [#permalink]

Show Tags

23 May 2010, 09:59
shekar123 wrote:
Could anyone help me with this question.

Two trains, Q and P, are traveling on straight and parallel tracks. Q and P are traveling at different constant rates. If train Q is now 3 miles ahead of train P, in how many minutes will train Q be 6 miles ahead of train P ?

(1) Train Q is traveling at a speed of 150 mph and train P is traveling at a speed of 120 mph.
(2) Four minutes ago, train Q was 1 mile ahead of train P.

It really helps if the stop watch is included in these questions .

Anyways, here is my take on this:

speed of P = v1
speed of Q = v2
Assuming they are traveling in the same direction
combined speed of P and Q = v2-v1
Distance in between them = 3 miles
Time required by train Q to be 6 miles ahead = t
Distance needed by Q = 3 miles

1) v2 = 150 ad v1 = 120
t = d/v = 3/(150-120) = 3/30 hrs = 1/10 *(60) = 6 mins
Sufficient

2) So 4 mins ago train Q was 1 mile ahead, and now it is 3 miles ahead, this means it traveled 2 miles in 4 mins

Thus, combined speed = d/4 = 2/4
v2 - v1 = 2/4 miles per minute (note it is not mph)

from this we can find t = 3/(v2 - v1) = 3*4/2 = 6 mins
Sufficient

_________________

press kudos, if you like the explanation, appreciate the effort or encourage people to respond.

Intern
Joined: 27 Sep 2009
Posts: 41
Followers: 0

Kudos [?]: 85 [0], given: 4

Re: Data sufficiency - 600 level question [#permalink]

Show Tags

23 May 2010, 15:52
dimitri92 wrote:
shekar123 wrote:
Could anyone help me with this question.

Two trains, Q and P, are traveling on straight and parallel tracks. Q and P are traveling at different constant rates. If train Q is now 3 miles ahead of train P, in how many minutes will train Q be 6 miles ahead of train P ?

(1) Train Q is traveling at a speed of 150 mph and train P is traveling at a speed of 120 mph.
(2) Four minutes ago, train Q was 1 mile ahead of train P.

It really helps if the stop watch is included in these questions .

Anyways, here is my take on this:

speed of P = v1
speed of Q = v2
Assuming they are traveling in the same direction
combined speed of P and Q = v2-v1
Distance in between them = 3 miles
Time required by train Q to be 6 miles ahead = t
Distance needed by Q = 3 miles

1) v2 = 150 ad v1 = 120
t = d/v = 3/(150-120) = 3/30 hrs = 1/10 *(60) = 6 mins
Sufficient

2) So 4 mins ago train Q was 1 mile ahead, and now it is 3 miles ahead, this means it traveled 2 miles in 4 mins

Thus, combined speed = d/4 = 2/4
v2 - v1 = 2/4 miles per minute (note it is not mph)

from this we can find t = 3/(v2 - v1) = 3*4/2 = 6 mins
Sufficient

sorry..i still can't get it.
Math Expert
Joined: 02 Sep 2009
Posts: 38846
Followers: 7720

Kudos [?]: 105948 [1] , given: 11602

Re: Data sufficiency - 600 level question [#permalink]

Show Tags

23 May 2010, 16:14
1
KUDOS
Expert's post
shekar123 wrote:
Could anyone help me with this question.

Two trains, Q and P, are traveling on straight and parallel tracks. Q and P are traveling at different constant rates. If train Q is now 3 miles ahead of train P, in how many minutes will train Q be 6 miles ahead of train P ?

(1) Train Q is traveling at a speed of 150 mph and train P is traveling at a speed of 120 mph.

(2) Four minutes ago, train Q was 1 mile ahead of train P.

Given distance between T and Q now is 3 miles (T---Q). Question in how many minutes distance will become 6 miles (T------Q), or in how many minutes Q will gain 3 more miles over T.

(1) Q is gaining 150-120=30 miles per hour over T. 3 miles will be gained in 1/10th of an hour, or in 6 minutes. Sufficient.

(2) As distance between T and Q now is 3 miles, therefore in 4 minutes Q gained over T 3-1=2 miles. 2 miles per 4 minute --> 3 miles will be gained in 1.5*4=6 minutes. Sufficient.

Hope it's clear.
_________________
Manager
Joined: 05 Jun 2013
Posts: 56
Location: India
Concentration: Entrepreneurship, General Management
GMAT 1: 640 Q48 V29
GPA: 3.6
Followers: 0

Kudos [?]: 11 [0], given: 31

Re: Two trains, Q and P, are traveling on straight and parallel [#permalink]

Show Tags

16 Oct 2013, 07:46
(1) Train Q is traveling at a speed of 150 mph and train P is traveling at a speed of 120 mph.

Distance between 2 objects is known ; and statement 1 gives speeds of both the objects; Now this information should be enough to get all the parameters, as speed=distance/time is just one equation with 3 variables.

(2) Four minutes ago, train Q was 1 mile ahead of train P.

According to statement 2, Q takes 4 minutes to create a gap of 2 miles, so wrt to P, we can calculate its speed (relative speed). Hence this is sufficient.

There is no need to solve this numerically.

--
Kudos are appreciated.
Re: Two trains, Q and P, are traveling on straight and parallel   [#permalink] 16 Oct 2013, 07:46
Similar topics Replies Last post
Similar
Topics:
Stations M and N are connected by two separate, straight and parallel 1 28 Apr 2016, 14:24
12 While on straight, parallel tracks, train A and train B are traveling 5 05 Dec 2015, 12:48
10 Two trains 1& 2 start simultaneously and run on parallel 4 19 Sep 2016, 04:07
9 In the figure above, P and Q are centers of two identical 11 29 Nov 2016, 13:41
2 Lines P, Q and R are parallel to each other.Is the slope ok 8 01 Oct 2016, 21:41
Display posts from previous: Sort by