It is currently 24 Nov 2017, 04:44

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

If a, b, c, and d, are positive numbers, is a/b < c/d?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Intern
Intern
avatar
B
Joined: 10 Nov 2016
Posts: 6

Kudos [?]: [0], given: 97

GMAT ToolKit User
Re: If a, b, c, and d, are positive numbers, is a/b < c/d? [#permalink]

Show Tags

New post 27 Apr 2017, 03:06
catty2004 wrote:
If a, b, c, and d, are positive numbers, is a/b < c/d?

(1) 0 < (c-a) / (d-b)

(2) (ad/bc)^2 < (ad)/(bc)



This is perhaps off topic but it caught my attention. How can a square of a number x be strictly less than x? I can't seem to find it logical.

Kudos [?]: [0], given: 97

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42356

Kudos [?]: 133196 [0], given: 12439

Re: If a, b, c, and d, are positive numbers, is a/b < c/d? [#permalink]

Show Tags

New post 27 Apr 2017, 03:13
samia33 wrote:
catty2004 wrote:
If a, b, c, and d, are positive numbers, is a/b < c/d?

(1) 0 < (c-a) / (d-b)

(2) (ad/bc)^2 < (ad)/(bc)



This is perhaps off topic but it caught my attention. How can a square of a number x be strictly less than x? I can't seem to find it logical.


x^2 < x is true for 0 < x < 1.

For example, (1/2)^2 < 1/2.

Check the links below for more:
Inequality tips

Inequalities Made Easy!

Solving Quadratic Inequalities - Graphic Approach

Wavy Line Method Application - Complex Algebraic Inequalities

DS Inequalities Problems
PS Inequalities Problems

Hope it helps.
_________________

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 [?]: 133196 [0], given: 12439

Manager
Manager
avatar
B
Joined: 29 Jun 2017
Posts: 157

Kudos [?]: 10 [0], given: 367

Re: If a, b, c, and d, are positive numbers, is a/b < c/d? [#permalink]

Show Tags

New post 14 Jul 2017, 08:03
for number property problem, we at first try to change the form of the expression.
if we can not change, or the change dose not bring any result, thinking of PICKING THE SPECIFIC NUMBERS.

choice A dose not imply a change in form of expression. so, we pick the specific numbers

Kudos [?]: 10 [0], given: 367

Manager
Manager
avatar
B
Joined: 30 Apr 2013
Posts: 91

Kudos [?]: [0], given: 9

CAT Tests
Re: If a, b, c, and d, are positive numbers, is a/b < c/d? [#permalink]

Show Tags

New post 14 Oct 2017, 08:36
Statement 2 is clearly sufficient but for statement 1 am bit confused- can someone clarify?

1) 0 < c-a/d-b

Can we simplify it to a+d < c + b ? If yes, am stuck here. how do I go forward?

Kudos [?]: [0], given: 9

Expert Post
Director
Director
User avatar
B
Joined: 17 Dec 2012
Posts: 623

Kudos [?]: 535 [0], given: 16

Location: India
Re: If a, b, c, and d, are positive numbers, is a/b < c/d? [#permalink]

Show Tags

New post 14 Oct 2017, 19:59
catty2004 wrote:
If a, b, c, and d, are positive numbers, is \(\frac{a}{b} < \frac{c}{d}\)?

(1) \(0 < \frac{(c-a)}{(d-b)}\)

(2) \((\frac{ad}{bc})^2 < \frac{(ad)}{(bc)}\)


Plug in Approach

Statement 1: a and b and also c and d can each be different numbers for the same value of a/b and c/d resp. Hence will give different answers and not sufficient

Statement 2: At least one of a/b or d/c is less than 1 and the other has a ceiling on its value. For convenience we will round values to one decimal.

If d/c =0.9, a/b should be less than 1.1. Since d/c=0.9, c/d=1.1. Hence c/d >a/b
If a/b=0.9, d/c should be less than 1.1, and c/d>0.9. Hence c/d>a/b
If both are less than 1, then c/d>a/b
Hence c/d in all the cases gretaer than a/b. Sufficient

Hence B.
_________________

Srinivasan Vaidyaraman
Sravna
http://www.sravnatestprep.com/regularcourse.php

Premium Material
Standardized Approaches

Kudos [?]: 535 [0], given: 16

Re: If a, b, c, and d, are positive numbers, is a/b < c/d?   [#permalink] 14 Oct 2017, 19:59

Go to page   Previous    1   2   [ 25 posts ] 

Display posts from previous: Sort by

If a, b, c, and d, are positive numbers, is a/b < c/d?

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


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®.