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

 It is currently 23 May 2017, 13:48

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

A and B walk from P to Q, a distance of 21km at 3 and 4

Author Message
Director
Joined: 24 Oct 2005
Posts: 659
Location: London
Followers: 1

Kudos [?]: 16 [0], given: 0

A and B walk from P to Q, a distance of 21km at 3 and 4 [#permalink]

Show Tags

04 May 2006, 07:31
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A and B walk from P to Q, a distance of 21km at 3 and 4 km/hr respectively. B reaches Q, and immediately returns and meets A at R. What is the distance btw P and R?
Director
Joined: 16 Aug 2005
Posts: 940
Location: France
Followers: 1

Kudos [?]: 23 [0], given: 0

Show Tags

04 May 2006, 07:54
P------------------------------R-------------Q

let distance between Q and R be x

Distance travelled by A is 21-x
Distance travelled by B is 21+x

time = distance/speed

So,
(21+x)/4 = (21-x)/3
=> 3(21 + x) = 4(21-x)
=> 63 + 3x = 84 - 4x
=> 7x = 21
=> x = 3

So, PR = 18 miles
Manager
Joined: 13 Aug 2005
Posts: 135
Followers: 1

Kudos [?]: 1 [0], given: 0

Show Tags

04 May 2006, 08:07
It would take B 21/4 hours to reach point Q.
During this time A walked 3*21/4 and the difference between the point where he is and Q at the moment A reached Q is 21/4 miles.
Now they are walking toward each other: t - time they spend walking
t*(3+4)=21/4 => t=3/4. B would walk 4*3/4=3miles.
Then the distance is 21-3=18 miles.
Manager
Joined: 13 Dec 2005
Posts: 224
Location: Milwaukee,WI
Followers: 1

Kudos [?]: 8 [0], given: 0

Show Tags

04 May 2006, 08:51
they totally walked 21*2 =42 miles because B travelled 21 Plus X and A travelled 21 minus X so 42 miles

42 miles at a speed of 7 miles per hr so they walked for 6 hour

A travelled 6 *3 = 18 miles and thats the distance between P & R
Manager
Joined: 14 Mar 2006
Posts: 208
Followers: 2

Kudos [?]: 9 [0], given: 0

Show Tags

04 May 2006, 08:53
I find it much easier to do these type of questions with a Chart, its called RDT chart, just a suggestion. Agree with the asnwer.
Senior Manager
Joined: 29 Jun 2005
Posts: 403
Followers: 2

Kudos [?]: 21 [0], given: 0

Show Tags

05 May 2006, 04:08
P_______________________T________R___Q
The distance between P and R = PT + TR
B reaches Q in 21/4=5,25 hours. In 5.25 hours A passes 3*5.25=15.75 km PT=15.75
P_________15.75__________T___5.25_R____Q
Then, B starts back, while A is still on its way to Q
The distance between A and B Is 5.25, the speeds are 3 and 4, so we have to do next is to find when they will meet:
5.25/(3+4)=0.75 hour. In 0.75 hour A will pass additional 0.75*3=2.25 km TR=2.25
Manager
Joined: 27 Mar 2006
Posts: 136
Followers: 1

Kudos [?]: 1 [0], given: 0

Show Tags

07 May 2006, 14:19
Agree with 18
07 May 2006, 14:19
Display posts from previous: Sort by