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

It is currently 22 Jul 2018, 23:17

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

500 records have a distribution that is symmetric about the mean 10.

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

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47188
500 records have a distribution that is symmetric about the mean 10.  [#permalink]

Show Tags

New post 06 Oct 2017, 02:17
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

75% (01:15) correct 25% (01:04) wrong based on 55 sessions

HideShow timer Statistics

500 records have a distribution that is symmetric about the mean 10. If 68 percent of the distribution lies within one standard deviation of the mean, and the deviation is 2, then at least how many of the records are less than 12?

(A) 160
(B) 320
(C) 340
(D) 420
(E) 460

_________________

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

Intern
Intern
avatar
B
Joined: 29 Dec 2016
Posts: 2
Location: India
Concentration: Marketing, Strategy
GMAT 1: 680 Q47 V36
GPA: 4
WE: Design (Computer Software)
Re: 500 records have a distribution that is symmetric about the mean 10.  [#permalink]

Show Tags

New post 06 Oct 2017, 02:35
Bunuel wrote:
500 records have a distribution that is symmetric about the mean 10. If 68 percent of the distribution lies within one standard deviation of the mean, and the deviation is 2, then at least how many of the records are less than 12?

(A) 160
(B) 320
(C) 340
(D) 420
(E) 460



Mean = 10 ; Deviation = 2. Therefore value pair of standard deviation = 8,12.
68% lies between value 8 and 12. And 16% less than 8.
Therefore, total 84% less than 12.
84% of 500 = 420.
Option D.
SC Moderator
avatar
D
Joined: 22 May 2016
Posts: 1837
Premium Member CAT Tests
Re: 500 records have a distribution that is symmetric about the mean 10.  [#permalink]

Show Tags

New post 06 Oct 2017, 13:55
4
Bunuel wrote:
500 records have a distribution that is symmetric about the mean 10. If 68 percent of the distribution lies within one standard deviation of the mean, and the deviation is 2, then at least how many of the records are less than 12?

(A) 160
(B) 320
(C) 340
(D) 420
(E) 460

Attachment:
nnnnnnn.png
nnnnnnn.png [ 8.79 KiB | Viewed 539 times ]

If the normal distribution is familiar, finding the answer should be quick.

1. Normal distribution
It is a normal distribution because 68 percent of the distribution lies within one standard deviation of the mean.
--- Half of that 68% lies to the right of mean (diagram: +1 SD on right and -1 SD on left)
--- Half of 68% for +1 SD is 34%. (mean 50% + 34%) = 84%

2) Value of 12 corresponds with 84% of distribution
Mean is 10, SD is 2: 12 is 10 (mean) + 2 (1 SD) which is equivalent to 84 percent of the distribution (on diagram, horizontal lines' vertical marks correspond)

3) At least how many of the records are less than 12?
Less than 12 = 34% + 34% + 14% + 2% (all intervals, 84 to 0, see shaded areas) = 84%

4) 500 records, 84 percent of which are less than 12: .84 * 500 = 420

Answer (D)
_________________

In the depths of winter, I finally learned
that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"

Re: 500 records have a distribution that is symmetric about the mean 10. &nbs [#permalink] 06 Oct 2017, 13:55
Display posts from previous: Sort by

500 records have a distribution that is symmetric about the mean 10.

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

Events & Promotions

PREV
NEXT


cron

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®.