
Probability and Statistics Basic Probability and Statistics Math Forum 
 LinkBack  Thread Tools  Display Modes 
June 16th, 2013, 09:26 PM  #1 
Newbie Joined: Jun 2013 Posts: 13 Thanks: 0  Probability
The probability of the students studying in Science is 30, and in Commerce is 45, and there are 10 students who study both, find the total number of students in the class ?

June 17th, 2013, 05:58 AM  #2 
Math Team Joined: Sep 2007 Posts: 2,409 Thanks: 6  Re: Probability
Where did you get this problem? You titled this "Probability" but surely if you were taking a probability class you would understand that a "probability" is always between 0 and 1. "The probability of the students studying in Science is 30" is impossible. I suspect that the problem says that there are 30 students studying Science. If there are 45 studying Commerce, do you see why "the number who are studying both" is not just 30+ 45? It is because, that way, you are counting the 10 students who are studying both. If there are 30 students studying Science and 10 of those are also studying Commerce, how many are studying Science only? If there are 45 students studying Commerce and 10 of those are also studying Science, how many are studying Commerce only? Now, can you answer the question? 

Tags 
probability 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
probability set theory  probability of x out of n events  hbonstrom  Applied Math  0  November 17th, 2012 07:11 PM 
Joint probability density function, probability  token22  Advanced Statistics  2  April 26th, 2012 03:28 PM 
Probability (probability mass function,pmf)  naspek  Calculus  1  December 15th, 2009 01:18 PM 