BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

OG 12 Data Sufficiency 173 (Hard as Hell)

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 162
Joined: Sun Aug 09, 2009 4:17 pm
Location: Minnesota
Thanked: 1 times

OG 12 Data Sufficiency 173 (Hard as Hell)

by EMAN » Mon Oct 05, 2009 6:35 pm
If arc PQR above is a semicircle, what is the length of diameter PR?

(1) a = 4
(2) b = 1

Please refer to page 288 for the diagram. I would like to know why in the explanation they say that PQ + QR is basically the same length as a + b. The substitution used in the explanation is confusing.
Top
Source: — Data Sufficiency |
Senior | Next Rank: 100 Posts
Posts: 33
Joined: Thu Apr 16, 2009 6:58 am
Location: Boston
Thanked: 2 times

Clear explanation for OG12 DS# 173

by bynddrvn » Tue Nov 03, 2009 6:26 am
Some of the Official Guide solutions are not very clear. Question #173 for the 12th edition was question #152 in the 11th edition. I found this video on youtube, and I think it is a much clearer explanation for this problem.

https://www.youtube.com/watch?v=dmN_s286dHc
Top
Master | Next Rank: 500 Posts
Posts: 324
Joined: Thu Dec 24, 2009 6:29 am
Thanked: 17 times
Followed by:1 members

by rahul.s » Sun Feb 21, 2010 6:58 am
this was a difficult problem. i just checked out that video solution on youtube and it was really helpful.
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 143
Joined: Sat Nov 06, 2010 9:06 pm
Thanked: 10 times
Followed by:1 members

by edvhou812 » Sun Sep 04, 2011 4:12 pm
Ha. I got this one right. :) By looking at both options, I was able to see that there is enough information to determine the size of the inscribed triangles. Although I have neglected the study of chords and segments for circles, I deducted that if we know the size of all of sides of any of the triangles, we must know the size of PQ and QR which means we must have enough information to find the size of PR/diameter.

1) a=4. Gives enough information to determine the size of the larger triangle that includes points P and Q (Sufficient)

2) b=1. Gives enough information to determine the size of the smaller triangle that includes points Q and R. (Sufficient)

Answer: D
I don't know what to say, really. Three minutes to the biggest battle of our professional lives. You find out life's this game of inches, so is football. Because in either game - life or football - the margin for error is so small. I mean, one half a step too late or too early and you don't quite make it. One half second too slow, too fast and you don't quite catch it. I'll tell you this, in any fight it's the guy whose willing to die whose gonna win that inch. That's football guys, that's all it is. Now, what are you gonna do?
Top
Master | Next Rank: 500 Posts
Posts: 381
Joined: Wed May 19, 2010 10:15 pm
Thanked: 41 times
Followed by:2 members

by AbhiJ » Mon Sep 05, 2011 2:12 am
You can use similarity between two triangles to reach to a faster solution
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Mon Sep 05, 2011 5:27 am
I posted solutions to similar problems here:

https://www.beatthegmat.com/inscribed-tr ... 74152.html

https://www.beatthegmat.com/length-of-th ... 71979.html

https://www.beatthegmat.com/geo-question ... nta-14-649
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 116
Joined: Wed Mar 14, 2012 1:02 pm
Thanked: 20 times
Followed by:11 members
GMAT Score:760

by mcdesty » Wed Dec 19, 2012 5:57 pm
See Image
Attachments
Note_1_01(1).jpg
Last edited by mcdesty on Wed Jul 09, 2014 9:53 am, edited 1 time in total.
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 116
Joined: Wed Mar 14, 2012 1:02 pm
Thanked: 20 times
Followed by:11 members
GMAT Score:760

by mcdesty » Wed Jul 09, 2014 9:53 am
See Img
Attachments
Gmat_13.jpg
Top
Post new topic Post Reply
• Page 1 of 1