Odd Problem

This topic has expert replies
User avatar
Legendary Member
Posts: 504
Joined: Tue Apr 19, 2011 1:40 pm
Thanked: 114 times
Followed by:11 members

Odd Problem

by knight247 » Sun Sep 18, 2011 4:17 am
If a number is drawn at random from the first 1000 positive integers, what is the probability of selecting a refined number?
(1)Any refined number must be divisible by 22
(2)A refined number is any even multiple of 11

User avatar
Master | Next Rank: 500 Posts
Posts: 279
Joined: Fri Nov 05, 2010 5:43 pm
Thanked: 15 times
Followed by:1 members

by mehrasa » Sun Sep 18, 2011 4:48 am
I did not solve the problem mathematically.. but i think each statement alone is sufficient... since both set of refined No. are the same and we can find out the number of ech even to find the probability
IMO:D

User avatar
Master | Next Rank: 500 Posts
Posts: 496
Joined: Tue Jun 07, 2011 5:34 am
Thanked: 38 times
Followed by:1 members

by sl750 » Sun Sep 18, 2011 5:26 am
Statement 1

Refined numbers could be 22,44,66.....990 We can find the probability of selecting a refined number. Sufficient

Statement 2

Even multiples of 11 are 22, 44, 66...This is the same as statement 1. Sufficient

User avatar
Master | Next Rank: 500 Posts
Posts: 312
Joined: Tue Aug 02, 2011 3:16 pm
Location: New York City
Thanked: 130 times
Followed by:33 members
GMAT Score:780

by gmatboost » Tue Sep 20, 2011 8:20 pm
The GMAT would never use an unknown term in a question without defining it in the question itself.

I would answer B to this question, but it is a matter of being very picky about the language and has nothing do to with math, so this is not really a GMAT math question.
(1)Any refined number must be divisible by 22
This doesn't actually say that a refined number is a multiple of 22. It says it MUST be a multiple of 22, but there might be other conditions we don't know about.

(2)A refined number is any even multiple of 11
This actually says that a refined number is a multiple of 22.

Again, not really a GMAT question.
Greg Michnikov, Founder of GMAT Boost

GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.


Also, check out the most useful GMAT Math blog on the internet here.

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Wed Sep 21, 2011 6:35 am
This would be closer to an actual GMAT question if there were some wording in the question stem explaining that "refined numbers" is a fictitious term.

I also have a problem with the term "even multiple." Although the definition might be intuitively apparent, I believe the GMAT test-makers would provide additional text to avoid any ambiguity.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image