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

It is currently 20 Oct 2014, 23:46

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

A contest will consist of n questions, each of which is to

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
VP
VP
avatar
Joined: 22 Nov 2007
Posts: 1102
Followers: 6

Kudos [?]: 135 [0], given: 0

A contest will consist of n questions, each of which is to [#permalink] New post 27 Dec 2007, 08:28
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

80% (01:00) correct 20% (00:12) wrong based on 28 sessions
A contest will consist of n questions, each of which is to be answered either "true" or " false". anyone who answers all n questions correctly will be a winner. what is the least value of n for which the probability is less than 1/1000 that a person who randomly guesses the answer to each question will be a winner?

A.5
B.10
C.50
D.100
E.1000
Director
Director
User avatar
Joined: 12 Jul 2007
Posts: 867
Followers: 12

Kudos [?]: 201 [0], given: 0

 [#permalink] New post 27 Dec 2007, 09:37
Each question has 2 ways to guess so the probability of guessing correctly is 1/2. The probability of guessing each question correctly for n questions is 1/2^n. What is the smallest number for n that gets the denominator over 1000?

1/2^n = probability

1/2^5 = 1/32
1/2^10 = 1/1024

and you don't need to go any further. Someone guessing on 10 questions has a 1/1024 chance of getting them all correct.

Answer: B
Manager
Manager
avatar
Joined: 27 Oct 2008
Posts: 186
Followers: 1

Kudos [?]: 79 [0], given: 3

Re: prob [#permalink] New post 27 Sep 2009, 10:29
A contest will consist of n questions, each of which is to be answered either "true" or " false". anyone who answers all n questions correctly will be a winner. what is the least value of n for which the probability is less than 1/1000 that a person who randomly guesses the answer to each question will be a winner?

A.5
B.10
C.50
D.100
E.1000

Soln: ans is B

Probability that one question is answered right is 1/2.

Now for minimum number of questions needed to take probability less than 1/1000 is
=> (1/2)^n < 1/1000
n = 10 satisfies this.
VP
VP
avatar
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1364
Followers: 12

Kudos [?]: 144 [0], given: 10

Re: prob [#permalink] New post 02 May 2011, 08:41
1/2^n < 1/1000

n= 10 is the least value of number of questions. 1/2 is for equal probability of true and false.
_________________

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

Re: prob   [#permalink] 02 May 2011, 08:41
    Similar topics Author Replies Last post
Similar
Topics:
2 A contest will consist of N questions, each of which is to study 2 08 Nov 2008, 03:33
15 Experts publish their posts in the topic A contest will consist of n questions, each of which is to tarek99 14 21 Nov 2007, 15:13
3 Experts publish their posts in the topic A contest will consist of n questions, each of which is to SimaQ 3 18 Nov 2006, 08:48
A contest will consist of n questions, each of which is to lfox2 2 15 Oct 2006, 22:48
A contest will consist of n questions, each of which is to rigger 2 24 Oct 2005, 23:04
Display posts from previous: Sort by

A contest will consist of n questions, each of which is to

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.