Find all School-related info fast with the new School-Specific MBA Forum

It is currently 30 Sep 2014, 22:22

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

GMAT Diagnostic Test Question 18

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Senior Manager
Senior Manager
User avatar
Joined: 19 Apr 2011
Posts: 291
Schools: Booth,NUS,St.Gallon
Followers: 4

Kudos [?]: 85 [0], given: 51

Re: GMAT Diagnostic Test Question 18 [#permalink] New post 06 Feb 2012, 21:30
Nice explanation everyone !!had got this question wrong !!
_________________

+1 if you like my explanation .Thanks :)

Manager
Manager
avatar
Joined: 17 Sep 2011
Posts: 209
Followers: 0

Kudos [?]: 19 [0], given: 8

Re: GMAT Diagnostic Test Question 18 [#permalink] New post 07 Feb 2012, 00:32
The answer is A. Very good Q.
_________________

_________________
Giving +1 kudos is a better way of saying 'Thank You'.

Intern
Intern
avatar
Joined: 05 Feb 2012
Posts: 2
Followers: 0

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

Re: GMAT Diagnostic Test Question 18 [#permalink] New post 08 Feb 2012, 01:08
and what if the members of S are negative numbers? nothing in the question states that S is composed of at least one positive number... am I mistaken? in that case, we need both statements: answer is C ... (????????)
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23064
Followers: 3539

Kudos [?]: 27255 [0], given: 2725

Re: GMAT Diagnostic Test Question 18 [#permalink] New post 08 Feb 2012, 03:27
Expert's post
nbrianco wrote:
and what if the members of S are negative numbers? nothing in the question states that S is composed of at least one positive number... am I mistaken? in that case, we need both statements: answer is C ... (????????)


Hi and welcome to GMAT Club! Below is an answer to your doubt.

Is the mean of set S greater than its median?

First of all:
The median of a set with odd # of terms is just a middle term (when ordered in ascending/descending order).

The median of a set with even # of terms is the average of two middle terms (when ordered in ascending/descending order).

Next, one of the most important properties of evenly spaced set (aka arithmetic progression):
In any evenly spaced set the arithmetic mean (average) is equal to the median and can be calculated by the formula mean=median=\frac{a_1+a_n}{2}, where a_1 is the first term and a_n is the last term. Given the set \{7,11,15,19\}, mean=median=\frac{7+19}{2}=13.

(1) All members of S are consecutive multiples of 3 --> S is an evenly spaced set, thus its mean equals to its median. Sufficient.

To address your question, lets check whether it's true if S consists with negative numbers:
{-6, -3} --> mean=-4.5=median;
{-9, -6, -3} --> mean=-6=median;
{-6, -3, 0, 3} --> mean=-1.5=median.

(2) The sum of all members of S equals 75. Clearly insufficient.

Answer: A.

For more on this topic check Number Theory chapter of Math Book: math-number-theory-88376.html

Hope it helps.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
avatar
Joined: 05 Feb 2012
Posts: 2
Followers: 0

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

Re: GMAT Diagnostic Test Question 18 [#permalink] New post 08 Feb 2012, 03:44
Thanks so much! I feel terrible as i completely misread the first assumption. This was not difficult indeed... sorry :(
Intern
Intern
avatar
Joined: 15 Apr 2011
Posts: 49
Followers: 0

Kudos [?]: 1 [0], given: 8

GMAT ToolKit User
Re: GMAT Diagnostic Test Question 18 [#permalink] New post 22 Feb 2012, 12:17
I solved it in a similar fashion. This was not bad at all...
Re: GMAT Diagnostic Test Question 18   [#permalink] 22 Feb 2012, 12:17
    Similar topics Author Replies Last post
Similar
Topics:
8 Experts publish their posts in the topic GMAT Diagnostic Test Question 32 bb 11 06 Jun 2009, 22:14
11 Experts publish their posts in the topic GMAT Diagnostic Test Question 27 bb 4 06 Jun 2009, 22:09
26 Experts publish their posts in the topic GMAT Diagnostic Test Question 24 bb 36 06 Jun 2009, 22:03
6 Experts publish their posts in the topic GMAT Diagnostic Test Question 20 bb 6 06 Jun 2009, 21:58
27 Experts publish their posts in the topic GMAT Diagnostic Test Question 1 bb 30 05 Jun 2009, 21:30
Display posts from previous: Sort by

GMAT Diagnostic Test Question 18

  Question banks Downloads My Bookmarks Reviews Important topics  

Go to page   Previous    1   2   [ 26 posts ] 

Moderators: Bunuel, WoundedTiger



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

Powered by phpBB © phpBB Group and phpBB SEO

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®.