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

It is currently 19 Apr 2014, 14:11

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

Math Questions Mean Score

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
Joined: 18 Dec 2009
Posts: 14
Followers: 0

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

Math Questions Mean Score [#permalink] New post 28 Dec 2009, 10:58
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

83% (01:27) correct 16% (01:26) wrong based on 6 sessions
Hello,

Here is the statement:

"For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean, what was the mean score for the examination?"
Choices: 74, 76, 80, 82
Correct answer: 74

I am not familiar with deviation.

Thanks in advance
Tuck Thread Master
User avatar
Joined: 20 Aug 2009
Posts: 312
Location: Tbilisi, Georgia
Schools: Stanford (in), Tuck (WL), Wharton (ding), Cornell (in)
Followers: 12

Kudos [?]: 82 [0], given: 69

GMAT Tests User
Re: Math Questions Mean Score [#permalink] New post 28 Dec 2009, 11:24
Definition and properties of StDev are not crucial for this problem.

let's denote deviation with x

Quote:
a score of 58 was 2 standard deviations below the mean

58=mean-2x


Quote:
a score of 98 was 3 standard deviations above the mean

98=mean+3x

We have 2 equations and 2 variables. So this linear system of equations can be solved. let's just subtract Statement1 from Statement 2:
98-58=mean +3x-mean+2x
40=5x
x=8
mean=98-3x=98-24=74
Intern
Intern
Joined: 18 Dec 2009
Posts: 14
Followers: 0

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

Re: Math Questions Mean Score [#permalink] New post 28 Dec 2009, 11:29
Thanks very much Shalva !!!

Indeed with the definition of Mean, the problem is solving by himself.

I need to review some maths concepts :-D
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17321
Followers: 2875

Kudos [?]: 18401 [0], given: 2350

GMAT Tests User CAT Tests
Re: Math Questions Mean Score [#permalink] New post 28 Dec 2009, 11:29
Expert's post
nailgmattoefl wrote:
Hello,

Here is the statement:

"For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean, what was the mean score for the examination?"
Choices: 74, 76, 80, 82
Correct answer: 74

I am not familiar with deviation.

Thanks in advance


A score of 58 was 2 standard deviations below the mean --> 58=Mean-2d
A score of 98 was 3 standard deviations above the mean --> 98=Mean+3d

Solving above for Mean=74

For more about the Standard Deviation please check: Standard Deviation.
_________________

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

Intern
Intern
Joined: 10 Jul 2009
Posts: 2
Followers: 0

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

Standard Deviation [#permalink] New post 01 Jun 2010, 04:28
Can anyone help me with this problem please? It comes from the Gmat Testprep.

For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean. What was the mean score for the examination?

A. 74
B. 76
C. 78
D. 80
E. 82

The right answer is A.
1 KUDOS received
CIO
CIO
Joined: 02 Oct 2007
Posts: 1218
Followers: 85

Kudos [?]: 599 [1] , given: 334

GMAT ToolKit User GMAT Tests User
Re: Standard Deviation [#permalink] New post 01 Jun 2010, 05:41
1
This post received
KUDOS
Let d stand for Standard Deviation, M - for mean. We can construct a system of equations:

\begin{cases} M - 2d = 58 \\ M + 3d = 98 \end{cases}

After you subtract the first equation from the second, you get this equation:

5d = 40
d = 8

After plugging the value of d in the first equation, you get the value of M:

M = 58 + 2*8 = 74

I hope it helps you.
jessicavanessa wrote:
Can anyone help me with this problem please? It comes from the Gmat Testprep.

For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean. What was the mean score for the examination?

A. 74
B. 76
C. 78
D. 80
E. 82

The right answer is A.

_________________

Welcome to GMAT Club! :)
Facebook TwitterGoogle+LinkedIn
Want to solve GMAT questions on the go? GMAT Club iPhone app will help.
Please read this before posting in GMAT Club Tests forum
Result correlation between real GMAT and GMAT Club Tests
Are GMAT Club Test sets ordered in any way?

Take 15 free tests with questions from GMAT Club, Knewton, Manhattan GMAT, and Veritas.

Intern
Intern
Joined: 10 Jul 2009
Posts: 2
Followers: 0

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

Re: Standard Deviation [#permalink] New post 01 Jun 2010, 07:21
Thank you !
Very useful
Re: Standard Deviation   [#permalink] 01 Jun 2010, 07:21
    Similar topics Author Replies Last post
Similar
Topics:
New posts Math Question for those who scored 650+ jackson24nj 0 02 Dec 2004, 12:18
Popular new posts Math Question jothiip 13 24 Apr 2005, 10:49
New posts Question on postbacc math course to address Q score obeny81 0 17 Nov 2006, 12:24
New posts 1 mean question? keeshafey 1 06 Oct 2009, 08:33
New posts 1 Experts publish their posts in the topic Meaning of the question nksbits 1 15 Sep 2013, 06:06
Display posts from previous: Sort by

Math Questions Mean Score

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.