Author 
Message 
TAGS:

Hide Tags

Director
Joined: 29 Nov 2012
Posts: 854

Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
03 Oct 2013, 05:28
13
This post received KUDOS
21
This post was BOOKMARKED
Question Stats:
47% (03:00) correct 53% (02:57) wrong based on 481 sessions
HideShow timer Statistics
Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters? A. 250 B. 300 C. 350 D. 400 E. 500
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Click +1 Kudos if my post helped...
Amazing Free video explanation for all Quant questions from OG 13 and much more http://www.gmatquantum.com/og13th/
GMAT Prep software What if scenarios http://gmatclub.com/forum/gmatprepsoftwareanalysisandwhatifscenarios146146.html



Intern
Joined: 28 Jan 2013
Posts: 32

Re: Brenda and sally run in opposite direction on a circular tra [#permalink]
Show Tags
03 Oct 2013, 07:09
1
This post received KUDOS
Lets say respective speeds are B and S for Brenda and Sally and distance of the circular track be 2d.
1st case, they run half of the distance of the circular track before meeting since they are running in opposite direction. so,
dB/(B+S)=100 (Brinda covered 100 m)
2nd case, they run for full circular track and Sally covered 150m.
2dS/(B+S)=150
solve and we will get 3B = 4S
put this in any of the above equation and calculate for 2d = 350.



Math Expert
Joined: 02 Sep 2009
Posts: 43785

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
03 Oct 2013, 08:20
16
This post received KUDOS
Expert's post
14
This post was BOOKMARKED
fozzzy wrote: Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters?
A. 250 B. 300 C. 350 D. 400 E. 500 Nice problem. +1. First time together they run half of the circumference. Second time together they run full circumference. First time Brenda runs 100 meters, thus second time she runs 2*100 = 200 meters. Since second time (when they run full circumference) Brenda runs 200 meters and Sally runs 150 meters, thus the circumference is 200 + 150 = 350 meters. Answer: C.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 15 Sep 2013
Posts: 11

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
06 Oct 2013, 05:54
1
This post received KUDOS
Bunuel wrote: fozzzy wrote: Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters?
A. 250 B. 300 C. 350 D. 400 E. 500 Nice problem. +1. First time they run half of the circumference. Second time they run full circumference. First time Brenda runs 100 meters, thus second time she runs 2*100 = 200 meters. Since second time (when they run full cimcufrence) Brenda runs 200 meters and Sally runs 150 meters, thus the circumference is 200 + 150 = 350 meters. Answer: C. Hi Bunuel, Why do we assume that Brenda runs for 2*100 = 200 meters for the second part of the problem?



Intern
Joined: 02 Feb 2012
Posts: 29
GPA: 4

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
06 Oct 2013, 06:14
Bunuel wrote: fozzzy wrote: Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters?
A. 250 B. 300 C. 350 D. 400 E. 500 Nice problem. +1. First time they run half of the circumference. Second time they run full circumference. First time Brenda runs 100 meters, thus second time she runs 2*100 = 200 meters. Since second time (when they run full cimcufrence) Brenda runs 200 meters and Sally runs 150 meters, thus the circumference is 200 + 150 = 350 meters. Answer: C. Does opposite direction mean running towards each other or running behind each other?? Bunuel, could you please elaborate on the concept of running half the circumference and full circumference.. I am confused



Director
Joined: 14 Dec 2012
Posts: 832
Location: India
Concentration: General Management, Operations
GPA: 3.6

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
06 Oct 2013, 06:33
4
This post received KUDOS
1
This post was BOOKMARKED
avinashrao9 wrote: Bunuel wrote: fozzzy wrote: Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters?
A. 250 B. 300 C. 350 D. 400 E. 500 Nice problem. +1. First time they run half of the circumference. Second time they run full circumference. First time Brenda runs 100 meters, thus second time she runs 2*100 = 200 meters. Since second time (when they run full cimcufrence) Brenda runs 200 meters and Sally runs 150 meters, thus the circumference is 200 + 150 = 350 meters. Answer: C. Does opposite direction mean running towards each other or running behind each other?? Bunuel, could you please elaborate on the concept of running half the circumference and full circumference.. I am confused opposite direction means running towards each other ....if they run behind each other then its in same direction. moreover since starting point is diametrically opposite point and they are running towards each other so the sum of distances travelled by both will be equal to perimeter of semicircle. ==>this is the first meeting point. now from this point they are running opposite to each other again. so second time when they will meet ...sum of distance travelled by both will be equal to perimeter of full circle i.e full circumference. moreover since they have constant speed. for covering distance equal to semi circle==>brenda contributes 100 m now since speed is constant so for covering distance 2 times of distance equal to semicircle==>brenda will contribute 2*100 = 200 m hope its clear
_________________
When you want to succeed as bad as you want to breathe ...then you will be successfull....
GIVE VALUE TO OFFICIAL QUESTIONS...
GMAT RCs VOCABULARY LIST: http://gmatclub.com/forum/vocabularylistforgmatreadingcomprehension155228.html learn AWA writing techniques while watching video : http://www.gmatprepnow.com/module/gmatanalyticalwritingassessment : http://www.youtube.com/watch?v=APt9ITygGss



Intern
Joined: 15 Sep 2013
Posts: 11

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
06 Oct 2013, 06:54
blueseas wrote: Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters?
A. 250 B. 300 C. 350 D. 400 E. 500 Quote: moreover since they have constant speed. for covering distance equal to semi circle==>brenda contributes 100 m now since speed is constant so for covering distance 2 times of distance equal to semicircle==>brenda will contribute 2*100 = 200 m
hope its clear Aaahh. If Brenda accounts for 200 meters, then shouldn't Sally cover 150 meters + X meters for the entire track? Thanks!



Math Expert
Joined: 02 Sep 2009
Posts: 43785

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
06 Oct 2013, 08:20
pauc wrote: blueseas wrote: Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters?
A. 250 B. 300 C. 350 D. 400 E. 500 Quote: moreover since they have constant speed. for covering distance equal to semi circle==>brenda contributes 100 m now since speed is constant so for covering distance 2 times of distance equal to semicircle==>brenda will contribute 2*100 = 200 m
hope its clear Aaahh. If Brenda accounts for 200 meters, then shouldn't Sally cover 150 meters + X meters for the entire track? Thanks! No. Second time they rum full circumference and we are told that second time Sally runs 150 meters.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Director
Joined: 17 Dec 2012
Posts: 627
Location: India

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
06 Oct 2013, 18:47
fozzzy wrote: Brenda and Sally run in opposite direction on a circular track, starting at diametrically opposite points. They first meet after Brenda has run 100 meters. They next meet after Sally has run 150 meters past their first meeting point. Each girl runs at a constant speed. What is the length of the track in meters?
A. 250 B. 300 C. 350 D. 400 E. 500 1. Since they start from diametrically opposite points and they run in opposite directions, the first time they meet they would have together run half the circular track. So when together they run half the track , Brenda covers 100 m 2. Second time they meet , together, they would have covered the full circular track. 3. Brenda would have covered 200 m since she covers 100m m in the first case. 4. It is given, Sally covers 150 m. Total length of the full circular track is 200+150=350m
_________________
Srinivasan Vaidyaraman Sravna http://www.sravnatestprep.com
Premium Material Standardized Approaches



Intern
Joined: 06 Aug 2012
Posts: 18

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
29 Nov 2013, 12:41
Dear Brunel ,
Please explain with some diagram . I got answer but my view point is little different .



Math Expert
Joined: 02 Sep 2009
Posts: 43785

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
29 Nov 2013, 13:13



Manager
Joined: 07 Dec 2009
Posts: 107
GMAT Date: 12032014

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
06 Jul 2014, 13:52
seabhi wrote: sorry Bunuel, but how are you calculating that Brenda ran 200 m, its not mentioned that they met exactly after the same time, as they met before or double the time. Since together Brenda and Samuel ran half the circle and in that Brenda ran 100m, When they run the complete circle Brenda will run 2*100= 200 m



NonHuman User
Joined: 09 Sep 2013
Posts: 13846

Re: Brenda and Sally run in opposite direction on a circular tra [#permalink]
Show Tags
28 Oct 2017, 23:09
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: Brenda and Sally run in opposite direction on a circular tra
[#permalink]
28 Oct 2017, 23:09






