GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 22 Sep 2018, 06:46

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

Is a > b ?

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

Hide Tags

Intern
Intern
avatar
Joined: 16 Jun 2010
Posts: 2
Is a > b ?  [#permalink]

Show Tags

New post Updated on: 03 Sep 2015, 02:11
7
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

57% (01:10) correct 43% (00:53) wrong based on 343 sessions

HideShow timer Statistics

Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b

Originally posted by Maude on 25 Aug 2010, 02:11.
Last edited by Bunuel on 03 Sep 2015, 02:11, edited 1 time in total.
Renamed the topic and edited the question.
Manager
Manager
avatar
Joined: 02 Apr 2010
Posts: 101
Re: Is a > b ?  [#permalink]

Show Tags

New post 25 Aug 2010, 03:41
1
This type of problem is probably solved fastest by picking numbers. The key is to think about positive and negative numbers.

Statement 1:

Cross-multiply to obtain 10*a = 7*b

This will hold true e.g. if a = 7 and b = 10 => a < b, but also if a= -7 and b = -10 => a > b. Hence, statement A is not sufficient.

Statement 2:

I assume the statement reads a = (70 / 100)*b, otherwise it would contradict the first statement. Again cross-multiple and simplify the fraction to obtain 10*a = 7*b.

The second statement doesn't provide you with any additional information. Thus, E is the solution to this problem.
Manager
Manager
User avatar
Joined: 15 Apr 2010
Posts: 176
Re: Is a > b ?  [#permalink]

Show Tags

New post 25 Aug 2010, 03:42
1
both statements essentially say the same thing.. ratio: a:b=7:10 => 10a=7b;

now just plug in some values to see if you can get any definitive answers:

assume a=7, b=10 or a=14, b=20 and so on.... (a< b)

but there are negative answers as well.... a=-7, b=-10 => a > b

I would go with E.....
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 49303
Re: Is a > b ?  [#permalink]

Show Tags

New post 03 Sep 2015, 02:15
1
1
Maude wrote:
Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b


Notice that both statements give us the same info:

(1) a/b = 7/10
(2) a = 70/100*b --> a/b = 70/100 = 7/10.

Thus the answer is either D or E. It's not D because from a/b = 7/10 it could be that (a = 7) < (b = 10) as well as (a = -7) > (b = -10).

Answer: E.
_________________

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

Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6227
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Is a > b ?  [#permalink]

Show Tags

New post 04 Sep 2015, 04:45
Forget conventional ways of solving math questions. In DS, Variable approach is

the easiest and quickest way to find the answer without actually solving the

problem. Remember equal number of variables and equations ensures a solution.


Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b
==> transforming the original condition and the question using variable approach method, we have 2 variables (a,b) and in order to match the number of variables and equations we need 2 equations. Since there is 1 each in 1) and 2), C is likely the answer.

Using both 1) & 2) together, the answer is yes if a=-7, b=10, while the answer is no if a=7, b=10. Since the conditions and not suffiicent. the answer is E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Director
Director
avatar
P
Joined: 02 Oct 2017
Posts: 616
Re: Is a > b ?  [#permalink]

Show Tags

New post 10 Jul 2018, 10:29
(1) a/b = 7/10

Given only ratio
If multiplied term is negative then a>b
but if multiplied term is positive then b>a

Multiple cases so insufficient

(2) a = 70/100*b

rearranging gives statement 1 only
so insufficient

E is answer

Give kudos if it helps
Manager
Manager
User avatar
G
Joined: 18 Jun 2018
Posts: 156
Premium Member CAT Tests
Re: Is a > b ?  [#permalink]

Show Tags

New post 10 Sep 2018, 01:47
Maude wrote:
Is a > b ?

(1) a/b = 7/10

(2) a = 70/100*b


Is \(a>b \quad?\)

(1) \(\frac{a}{b} = \frac{7}{10}\)

Taking \(a = 7\) and \(b = 10,\quad \frac{a}{b}=\frac{7}{10}\)

Is \(a>b ? : No\) ; as \(7<10\).

Taking \(a = - 7\) and \(b = -10,\quad \frac{a}{b} = \frac{-7}{-10}=\frac{7}{10}\)

Is \(a>b ? : Yes\) ; as \(-7>-10\).

Statement \(1\) alone is not sufficient.

(2) \(a = \frac{70}{100}*b\)

\(a = \frac{70}{100}*b\) can be reduced to \(a = \frac{7}{10} *b\)

Taking \(a = 7\) and \(b = 10,\quad a=\frac{7}{10}*b\)

Is \(a>b ? : No\) ; as \(7<10\).

Taking \(a = - 7\) and \(b = -10,\quad a = \frac{7}{10}b\)

Is \(a>b ? : Yes\) ; as \(-7>-10\)

Statement \(2\) alone is not sufficient.

As Statement (1) and statement (2) are the same with only exception that in statement 1, b cannot be zero while statement 2, b can be 0.
Combining both will also be insufficient to answer: Is a > b ?
Re: Is a > b ? &nbs [#permalink] 10 Sep 2018, 01:47
Display posts from previous: Sort by

Is a > b ?

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

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.