4GMAT - Online GMAT Preparation

GMAT Practice Tests, Classes, Free Quizzes
It is currently Fri Sep 03, 2010 6:44 am

All times are UTC




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: probability
PostPosted: Mon Jun 09, 2008 2:12 pm 
Offline
Associate

Joined: Tue Apr 15, 2008 6:48 am
Posts: 2
If the probability of rain on any given day in City X is 50%, what is the probability that it rains on exactly 3 days in a 5 day period?

a. 8/125
b. 2/25
c. 5/16
d. 8/25
e. 3/4
Please provide me the solution with the required steps.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jun 11, 2008 2:47 am 
Offline
GMAT Tutor

Joined: Tue Dec 28, 2004 2:34 am
Posts: 81
Location: Chennai, India
The probability of it raining on any day is 1/2.

If it rains on exactly 3 out of the 5 days, then it does not rain on the other two days.

The probability it rains on exactly 3 days = probability of it raining for 3 days * probability of it not raining on the other 2 days * selecting 3 out of 5 days when it rains

= (1/2) ^3 * (1/2)^2 * 5C3 = (1/8 ) * (1/4) * 10 =10/32 = 5/16.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 0 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group

phpBB SEO