It is currently 19 Oct 2017, 11:43

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

The mean score in a certain test is 80. If the test scores have a norm

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

Hide Tags

2 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 08 Jan 2009
Posts: 325

Kudos [?]: 176 [2], given: 5

The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 31 Jul 2009, 20:08
2
This post received
KUDOS
5
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

53% (01:31) correct 47% (01:01) wrong based on 90 sessions

HideShow timer Statistics

The mean score in a certain test is 80. If the test scores have a normal distribution and the standarad distribution is 7, what percent of examinees score between 66 and 94?

A) 50%
B) 68%
C) 82%
D) 96%
E) 98%
[Reveal] Spoiler: OA

Kudos [?]: 176 [2], given: 5

Senior Manager
Senior Manager
avatar
Joined: 08 Jan 2009
Posts: 325

Kudos [?]: 176 [0], given: 5

Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 02 Aug 2009, 20:30
Thank you.

I read through the description now i get it.

The percentages 34: 14 : 2 corresponds to the 1st , 2nd and 3rd standard deviation on each side of the mean.

So our case 66 and 94 are two std deviation away from the mean.

14 + 34 + 34 + 14 = 96%

Kudos [?]: 176 [0], given: 5

Senior Manager
Senior Manager
avatar
Joined: 25 Jun 2009
Posts: 298

Kudos [?]: 150 [0], given: 6

Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 02 Aug 2009, 22:41
tkarthi4u wrote:
Thank you.

I read through the description now i get it.

The percentages 34: 14 : 2 corresponds to the 1st , 2nd and 3rd standard deviation on each side of the mean.

So our case 66 and 94 are two std deviation away from the mean.

14 + 34 + 34 + 14 = 96%


Hi,
Can you please explain how did you get that?

Thanks

Kudos [?]: 150 [0], given: 6

2 KUDOS received
Manager
Manager
User avatar
Joined: 18 Jul 2009
Posts: 167

Kudos [?]: 115 [2], given: 37

Location: India
Schools: South Asian B-schools
Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 07 Aug 2009, 07:27
2
This post received
KUDOS
1
This post was
BOOKMARKED
Normal distribution says

1 sigma = 68% (34% on either side) population
2 sigma = 96% (14% on either side) population so 68% +14%x 2=96%
3 sigma = 99.99% (2% on either side) population so 96% + 2% x 2 ~ 99.99 %
_________________

Bhushan S.
If you like my post....Consider it for Kudos :-D

Kudos [?]: 115 [2], given: 37

Manager
Manager
User avatar
Joined: 10 Jul 2009
Posts: 125

Kudos [?]: 183 [0], given: 60

Location: Ukraine, Kyiv
Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 16 Sep 2009, 08:23
Try wikipedia to make it clear.

http://en.wikipedia.org/wiki/Normal_distribution
_________________

Never, never, never give up

Kudos [?]: 183 [0], given: 60

Manager
Manager
avatar
Joined: 27 Oct 2008
Posts: 185

Kudos [?]: 164 [0], given: 3

Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 19 Sep 2009, 07:06
The mean score in a certain test is 80. If the test scores have a normal distribution and the standarad distribution is 7, what percent of examinees score between 66 and 94?

A) 50%
B) 68%
C)82%
D)96%
E)98%

Soln: Here mean = 80
and standard deviation sig = 7
Since for a range of scores from 66 to 94, the scores vary between 2 * sig about mean
that is from -2 * sig to +2 * sig
for this range with normal distribution the percent of examinees is
= 13.6 + 34.1 + 34.1 + 13.6
= 95.4
Approximately 96%
Ans is D

Kudos [?]: 164 [0], given: 3

VP
VP
avatar
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1285

Kudos [?]: 281 [0], given: 10

Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 18 May 2011, 00:28
interesting concept.

73 - 80 and 80-87 = 1 sigma = 34*2

66-73 and 87- 94 = 2 sigma = 14 * 2

total 96%
_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

Kudos [?]: 281 [0], given: 10

Manager
Manager
avatar
B
Joined: 20 Apr 2014
Posts: 116

Kudos [?]: [0], given: 23

Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 24 Sep 2015, 02:25
i need more explanation from experts please. will I see this type of Qs in Gmat Test ?

Kudos [?]: [0], given: 23

1 KUDOS received
Manager
Manager
User avatar
Joined: 23 Sep 2015
Posts: 94

Kudos [?]: 17 [1], given: 213

Concentration: General Management, Finance
GMAT 1: 680 Q46 V38
GMAT 2: 690 Q47 V38
GPA: 3.5
Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 07 Nov 2015, 22:41
1
This post received
KUDOS
This question is just testing standard knowledge of a normal distribution graph.

The mean=80, mean 50% of the data falls above and below this point,

When we consider 1 standard deviation on either side of it, we are cutting the data points of interest down to 34% on each side, or 68% between them

As for the question we are being asked about the range +/- 2 SD from the mean. This tests us just knowing that this represents 96% of the data of the data points, or 48% on either side of the mean.

Hope this helps someone

Kudos [?]: 17 [1], given: 213

CEO
CEO
User avatar
G
Joined: 17 Jul 2014
Posts: 2604

Kudos [?]: 394 [0], given: 184

Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge CAT Tests
Re: The mean score in a certain test is 80. If the test scores have a norm [#permalink]

Show Tags

New post 28 Nov 2015, 10:31
normal distribution represents the bell curve, in which 50% is above mean, and 50% below mean
34% lies within 1 standard deviation or mean+SD and mean-SD
mean+-SD is 73 and 87.
68% of people have scores between 73 and 87
now, aprox. 14% is between (mean+2SD)-(Mean+SD), this is the same for mean minus 2 SD.
Mean+2SD=94
Mean-2SD=66

ok, so in total, we have 68% + 28 = aprox. 98%.

Kudos [?]: 394 [0], given: 184

Re: The mean score in a certain test is 80. If the test scores have a norm   [#permalink] 28 Nov 2015, 10:31
Display posts from previous: Sort by

The mean score in a certain test is 80. If the test scores have a norm

  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®.