Find all School-related info fast with the new School-Specific MBA Forum

It is currently 23 Jul 2014, 08:28

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Yesterday's DS Challenge Question - solution here!

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 26 Jul 2010
Posts: 201
Followers: 91

Kudos [?]: 204 [1] , given: 20

Yesterday's DS Challenge Question - solution here! [#permalink] New post 18 Nov 2010, 14:37
1
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Hey everyone - sorry...yesterday's question was formatted as "competition mode" and I can't figure out how to undo it, so I don't think anyone has seen my response yet. Here it is:

_______________________________________________________________________________________________________________


Thanks for the responses, everyone! I love this question because of the strategy it brings up, which we call:

Why Are You Here?

Regarding statement 2, it's nowhere close to being sufficient on its own. So there are two likely reasons that it's there:

1) To trick you into thinking that you need it, and therefore picking C instead of A
2) To add information that IS, in fact, necessary to go with statement 1, so that the correct answer is C and not A

The GMAT doesn't use "red herring" statements - those that are simply so far out of scope that they're not even relevant - very often at all; if they provide a statement in a Data Sufficiency problem there has to be a reason...it's either a trap or it's necessary information. The good news for you is that you can use either case the same way: look at that statement to determine whether you really need it.

Here, although statement 1 may seem sufficient on its own (c must be 0 in order to make the 5 term equal to 1, since 1728 has no multiples of 5), that only fits if we know that they're all integers. Statement 2, by providing us with that information explicitly (they're nonnegative integers), should make us pause to think about statement 1: Do they have to be integers?

We don't need to use logarithms on the GMAT (thankfully!), but we should know enough that there would conceivably exist a set of noninteger exponents that would solve this problem. Even if you just assume that a and b are 1 so that:

5^c = 288

There is some value for c that will get us 288, so we can prove that statement 1 is not on its own sufficient. We need statement 2's help to determine that they're integers, so the correct answer is C.


So, strategically, when you see a statement that on its own is clearly not sufficient, ask yourself "why are you here?". Is it providing essential information, or is it there to make you think you need it?

_________________

Brian

Save $100 on live Veritas Prep GMAT Courses and Admissions Consulting

Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Kaplan Promo CodeKnewton GMAT Discount CodesVeritas Prep GMAT Discount Codes
Intern
Intern
User avatar
Joined: 25 Nov 2009
Posts: 46
Location: India
Followers: 3

Kudos [?]: 4 [0], given: 8

Re: Yesterday's DS Challenge Question - solution here! [#permalink] New post 18 Nov 2010, 20:23
A very good question indeed, I never use to think on these terms.....

_________________

When going gets tough, tough gets going.........

Manager
Manager
User avatar
Status: Starting Work
Affiliations: Chartered Engineer
Joined: 20 Jun 2010
Posts: 198
Location: United Arab Emirates
Concentration: General Management, Leadership
Schools: INSEAD - Class of 2013
WE: Business Development (Energy and Utilities)
Followers: 7

Kudos [?]: 27 [0], given: 19

Re: Yesterday's DS Challenge Question - solution here! [#permalink] New post 19 Nov 2010, 07:28
I picked the answer as A and now I figure out what was my mistake.

But still, its very difficult to think that in the expression 2^a * 3^b * 5^c = 1728, even with a,b and c taking non integer value we can get the product,1728.
Intern
Intern
User avatar
Joined: 16 Nov 2010
Posts: 2
Followers: 0

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

Re: Yesterday's DS Challenge Question - solution here! [#permalink] New post 20 Nov 2010, 18:36
Good question,I will go

_________________

Great minds think alike.

Re: Yesterday's DS Challenge Question - solution here!   [#permalink] 20 Nov 2010, 18:36
    Similar topics Author Replies Last post
Similar
Topics:
197 Experts publish their posts in the topic Quant 700-800 questions(PS+DS) with solutions satishchandraaily 60 11 Nov 2011, 20:24
3 Got a 47 Verbal yesterday, here's my method: kelli 5 27 Jun 2008, 17:35
Math DS questions - Help with solution vidyanan 3 13 Jun 2007, 07:11
Challenge 3, no. 8 - DS question successstory 3 22 Nov 2006, 16:10
DS: Solution mirhaque 6 08 Jul 2005, 06:23
Display posts from previous: Sort by

Yesterday's DS Challenge Question - solution here!

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.