NEW HERE? LEARN MORE
closeclose
Last visit was: 26 Apr 2024, 17:12 It is currently 26 Apr 2024, 17:12
Decision Tracker
My Rewards
New posts
New comers' posts

Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Wrong GMATPrep Problem

User avatar
shammokando
Intern
Intern
Joined: 08 Apr 2010
Posts: 16
Own Kudos [?]: 1 [0]
Given Kudos: 0
GPA: 3.7
Send PM
Wrong GMATPrep Problem [#permalink] New post   Updated on: 19 Apr 2010, 11:53
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Hide Show timer Statistics
Is this possible? I took a GMATPrep a few days ago and found 2 questions I'm pretty confident are wrong. I'll post the PS one here. Unfortunately, it's a picture so I'm just going to describe it.

It was on a coordinate plane with a semi circle resting ontop of the x-axis. It had a right angle drawn that looked to be bisected by the y axis. The angle intersected the circle twice, one in the left quadrant, once in the right.

The coordinates for the left intersection were "(-root3, 1) and the right intersection was (r,s). The question was, what is r?

Looking at this, the only answer I can understand is positive root3, since, if it's a right angle bisected by the y axis, the y's would be the same and the x would be the same absolute value.

However the answer given is 1. I understand that the picture could be misleading and the angle is not perfectly bisected, but if that were the case, the problem would be impossible to solve, not 1.

Any thoughts? If this is wrong, how can old GMAT questions (which is what the gmatprep software uses right?) be wrong??? Especially 2 of them?

Thanks!



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!

Originally posted by shammokando on 19 Apr 2010, 11:36.
Last edited by shammokando on 19 Apr 2010, 11:53, edited 1 time in total.
User avatar
ykaiim
Director
Director
Joined: 25 Aug 2007
Posts: 520
Own Kudos [?]: 5425 [0]
Given Kudos: 40
WE 1: 3.5 yrs IT
WE 2: 2.5 yrs Retail chain
Send PM
Re: Wrong GMATPrep Problem [#permalink] New post   19 Apr 2010, 11:38
Attach the screenshot. That will be easy.
User avatar
shammokando
Intern
Intern
Joined: 08 Apr 2010
Posts: 16
Own Kudos [?]: 1 [0]
Given Kudos: 0
GPA: 3.7
Send PM
Re: Wrong GMATPrep Problem [#permalink] New post   19 Apr 2010, 11:52
I resketched my copy of it (I copied it down, didn't think to screenshot, and now I can't access it again...)

Also, is there anyone I can look at my old test again? I thought I clicked for it to keep the test unfinished. It's making me take the test again if I click practice test 1... is this a new test?
Attachments

Gmatprep question.png
Gmatprep question.png [ 2.63 KiB | Viewed 2474 times ]

User avatar
chix475ntu
Manager
Manager
Joined: 26 May 2005
Posts: 99
Own Kudos [?]: 257 [0]
Given Kudos: 1
Send PM
Re: Wrong GMATPrep Problem [#permalink] New post   19 Apr 2010, 16:10
shammokando wrote:
The coordinates for the left intersection were "(-root3, 1) and the right intersection was (r,s). The question was, what is r?

Looking at this, the only answer I can understand is positive root3, since, if it's a right angle bisected by the y axis, the y's would be the same and the x would be the same absolute value.
Thanks!


the bolded assumption is not corrct. You are assuming that the angle between x axis and the line passing through (-root3, 1) is 45 but its not given in the question.

based on the information given
we know that the length of (-root3, 1) to origin and length of (r,s) to the origin are the same
so r^2 + s^2 = 4 ... I

and also as lines passing through (-root3, 1) and (r,s) are perpendicular, the product of slopes is -1

s/r * 1/-root3 = -1
s = r * -root3 ... II
substitutiona II in 1
r = 1
User avatar
fivezero7
Intern
Intern
Joined: 08 Apr 2010
Posts: 23
Own Kudos [?]: 13 [0]
Given Kudos: 3
Send PM
Re: Wrong GMATPrep Problem [#permalink] New post   Updated on: 20 Apr 2010, 00:09
shammokando wrote:
I resketched my copy of it (I copied it down, didn't think to screenshot, and now I can't access it again...)

Also, is there anyone I can look at my old test again? I thought I clicked for it to keep the test unfinished. It's making me take the test again if I click practice test 1... is this a new test?

hi,
you have mentioned that the angle between the two lines is a right angle.
however it is nowhere mentioned that the y-axis bisects the right angle.
so we will have to solve it using the slopes of the lines.
the slope of the line which passes through \((-\sqrt{3},1)\) and (0,0) when multiplied with the slope of the line which passes through (r,s) and (0,0) will give -1 as the product.

hence on finding the slopes of both equations, we can find out that r will be 1.

Originally posted by fivezero7 on 19 Apr 2010, 22:34.
Last edited by fivezero7 on 20 Apr 2010, 00:09, edited 1 time in total.
User avatar
shammokando
Intern
Intern
Joined: 08 Apr 2010
Posts: 16
Own Kudos [?]: 1 [0]
Given Kudos: 0
GPA: 3.7
Send PM
Re: Wrong GMATPrep Problem [#permalink] New post   19 Apr 2010, 22:43
Thanks! Very helpful

Posted from my mobile device
User avatar
shahideh
Manager
Manager
Joined: 25 May 2011
Posts: 60
Own Kudos [?]: 148 [0]
Given Kudos: 71
Send PM
Re: Wrong GMATPrep Problem [#permalink] New post   23 Oct 2011, 04:57
we have:

\(r^2+s^2=4\)
and
\(\frac{1}{\sqrt{3}}=\frac{r}{s}\)

So, r=1



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
GMAT Club Bot
gmatclubot
Re: Wrong GMATPrep Problem [#permalink]
23 Oct 2011, 04:57
Moderators:
Bunuel
Math Expert
92948 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions