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

 It is currently 23 Jun 2018, 14:18

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# A contest will contain n questions each of which is to be

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

### Hide Tags

Manager
Joined: 07 Feb 2010
Posts: 136
A contest will contain n questions each of which is to be [#permalink]

### Show Tags

02 Nov 2010, 06:31
1
5
00:00

Difficulty:

35% (medium)

Question Stats:

67% (01:22) correct 33% (01:28) wrong based on 205 sessions

### HideShow timer Statistics

A contest will contain 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 then 1/1000 then a person who randomly guesses the answer to each q's will be a winner?

A. 5
B. 10
C. 50
D. 100
E. 1000
Math Expert
Joined: 02 Sep 2009
Posts: 46297
Re: a contest will contain n questions [#permalink]

### Show Tags

02 Nov 2010, 06:48
2
1
anilnandyala wrote:
a contest will contain 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 probablity is less then 1/1000 then a person who randomly guesses the answer to each q's will be a winner?

a) 5
b) 10
c) 50
d) 100
e) 1000

The probability that a person will randomly guess all $$n$$ questions correctly is $$\frac{1}{2^n}$$, so we want the value of $$n_{min}$$ for which $$\frac{1}{2^n}<\frac{1}{1000}$$ --> $$2^n>1000$$ --> as $$n$$ is an integer $$n_{min}=10$$ ($$2^{10}=1024>1000$$).

Answer: B.
_________________
Manager
Joined: 06 Aug 2010
Posts: 192
Location: Boston
Re: a contest will contain n questions [#permalink]

### Show Tags

02 Nov 2010, 06:50
The probability of answering all the questions correctly is $$\frac{{1}}{{2^n}}$$. We want this probability to be less than $$\frac{1}{1,000}$$, so we need the smallest value of n that gives us $$2^n > 1,000$$. $$2^{10} = 1,024$$, so the answer is 10. B.
Non-Human User
Joined: 09 Sep 2013
Posts: 7041
Re: A contest will contain n questions each of which is to be [#permalink]

### Show Tags

20 Sep 2017, 21:16
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: A contest will contain n questions each of which is to be   [#permalink] 20 Sep 2017, 21:16
Display posts from previous: Sort by

# A contest will contain n questions each of which is to be

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

 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®.