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

It is currently 17 Sep 2014, 22:11

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

PS

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 01 Aug 2003
Posts: 48
Location: Mumbai
Followers: 1

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

PS [#permalink] New post 01 Aug 2003, 07:47
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Pls help
A certain telephone number has 7 digits.If the
telephone number has the digit 0 exactly three times
and number one is not used at all what is the
probability that phone number contains 1 or more prime
numbers?
Manager
Manager
avatar
Joined: 02 Jul 2003
Posts: 58
Followers: 1

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

I'll take a shot [#permalink] New post 01 Aug 2003, 08:56
eliminate three digits because 3 are zero. so last four digits could be 2,3.,4,5,6,7,8,9 for a totatl of 8^4 choices. Prime numbers are 2,3,5,7 so favorable outcomes are 4^4. so answer (hopefully)is 4^4/8^4.
SVP
SVP
User avatar
Joined: 03 Feb 2003
Posts: 1613
Followers: 6

Kudos [?]: 46 [0], given: 0

 [#permalink] New post 01 Aug 2003, 11:08
My approach:

P(at least 1 prime)=1-P(no primes)

Total outcomes: 8*8*8*8*1*1*1 - but this case is when 3 zeroes are the last digits. But it is not given. We have multiply by 6C3=20. So, 20*8^4

Favorable outcomes: 4*4*4*4*1*1*1*6C3=20*4^4

P=1-(4^4/8^4)=1-(1/16)=15/16
Manager
Manager
User avatar
Joined: 03 Jun 2003
Posts: 84
Location: Uruguay
Followers: 1

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

 [#permalink] New post 01 Aug 2003, 11:54
My try,

P(at least one prime) = 1- P (no prime)

7 numbers of which 3 are 0┬┤s and no 1┬┤s

So we have 4 numbers left to find out

primes (2,3,5,7) not primes (4,6,8,9)

first number P (not prime) = 4/8 = 1/2

so 1- (1/2)^4 = 15/16
  [#permalink] 01 Aug 2003, 11:54
    Similar topics Author Replies Last post
Similar
Topics:
ps: mirhaque 6 25 Apr 2005, 05:58
ps: mirhaque 1 22 Apr 2005, 13:46
ps mirhaque 6 23 Mar 2005, 06:04
ps: mirhaque 6 21 Feb 2005, 09:15
PS: mirhaque 5 21 Feb 2005, 05:43
Display posts from previous: Sort by

PS

  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®.