Error in OG 11?

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rjbrooks: Senior | Next Rank: 100 Posts; Posts: 37; Joined: Wed Jun 18, 2008 6:43 am; Location: Boston

Error in OG 11?

by rjbrooks » Mon Oct 13, 2008 8:25 am

Hey guys, correct me if I'm wrong, but take a look in OG 11 (Orange Book) for 3.1 Test # 23 - in the answer section it is stated as I. 24/8,
II. 24/8 and III. 24/8. Shouldn't this be 24/8, 24/12, and 24/18, respectively? Thanks.

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Source: Beat The GMAT — Problem Solving | Mon Oct 13, 2008 8:25 am

madeline: Senior | Next Rank: 100 Posts; Posts: 31; Joined: Tue Jul 22, 2008 9:09 am; Location: Toronto; Thanked: 7 times; GMAT Score:770

by madeline » Mon Oct 13, 2008 8:32 pm

My #23 in OG 11 goes like this:

If the positive integer x is a multiple of 4 and the positive integer y is a multiple of 6, then xy must be a multiple of which of the following?

I. 8
II. 12
III. 18

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bekkilyn: Senior | Next Rank: 100 Posts; Posts: 81; Joined: Mon Oct 06, 2008 9:06 am; Location: United States; Thanked: 5 times

by bekkilyn » Mon Oct 13, 2008 10:29 pm

I think s/he means the part of the answer that demonstrates how each possible answer is divided into 24 to see if the number is a divisor. Unless I'm looking in the wrong area, my book does show 24/8, 24/12, and 24/18 and then shows that 24 is not a multiple of 18, so the answer choices would be I. and II.

Perhaps there is a typo with some of the books?

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Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 am; Location: Montreal; Thanked: 1090 times; Followed by:355 members; GMAT Score:780

by Ian Stewart » Tue Oct 14, 2008 1:02 am

There are a few typos in earlier printings of the OG, though I don't think I've ever heard of an issue with this particular question. If you have an earlier printing (easy way to check: if in problem 20, pg. 154, E is pointing exactly at 2, you have an early version which has a few mistakes) then you should search on google for the pdf file from GMAC which lists the corrections. Even if you have the latest version, there are at least three mathematical errors in the book, which I pointed out in a blog entry here:

www.gmatix.com/blogging/index.php

For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

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