It is currently 16 Dec 2017, 08:50

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Test 16

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Joined: 19 Aug 2010
Posts: 72

Kudos [?]: 30 [0], given: 2

Test 16 [#permalink]

Show Tags

New post 30 Jan 2011, 12:40
If a, b ,c and d are non-zero numbers such that \(a/b=c/d\) and \(a/d=b/c\) , which of the following must be true?

• lal=lcl
• lbl=ldl
• lal=ldl
• lbl=lal
• lbl=lcl

This is a question from Test 16. OA is D although I receive every time lcl=ldl
Could someone help me?
Thanks

Kudos [?]: 30 [0], given: 2

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42629

Kudos [?]: 135833 [0], given: 12715

Re: Test 16 [#permalink]

Show Tags

New post 30 Jan 2011, 13:21
medanova wrote:
If a, b ,c and d are non-zero numbers such that \(a/b=c/d\) and \(a/d=b/c\) , which of the following must be true?

• lal=lcl
• lbl=ldl
• lal=ldl
• lbl=lal
• lbl=lcl

This is a question from Test 16. OA is D although I receive every time lcl=ldl
Could someone help me?
Thanks


Given: (i) \(\frac{a}{b}=\frac{c}{d}\) and (ii) \(\frac{a}{d}=\frac{b}{c}\).

Now, from (i) \(a=\frac{bc}{d}\) and substituting \(a\) in (ii) you'll get \(\frac{bc}{d^2}=\frac{b}{c}\) --> \(c^2=d^2\) --> \(|c|=|d|\) (so you are right), but this option is not listed among answer choices and you should try to get the one which is listed.

Again, from (i) \(c=\frac{ad}{b}\) and substituting \(c\) in (ii) you'll get \(\frac{a}{d}=\frac{b^2}{ad}\) --> \(a^2=b^2\) --> \(|a|=|b|\).

Answer: D.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Kudos [?]: 135833 [0], given: 12715

Re: Test 16   [#permalink] 30 Jan 2011, 13:21
Display posts from previous: Sort by

Test 16

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderator: Bunuel



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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.