
Probability and Statistics Basic Probability and Statistics Math Forum 
 LinkBack  Thread Tools  Display Modes 
March 18th, 2011, 03:55 PM  #1 
Member Joined: Aug 2009 Posts: 69 Thanks: 0  Probability practice problems?
Soz... I have an important standardized test tomorrow... and usually these things are really easy, but I've forgotten most of the stuff I've learned about probability. One question that really tripped me up: You have 6 white marbles, 4 green marbles, and 5 blue marbles in a bag. If you draw four marbles at random, what's the probability of getting at least one of each color? So... how do you solve this question? And what are some good websites for practicing probabilities? 
March 21st, 2011, 06:47 AM  #2 
Senior Member Joined: Feb 2009 From: Adelaide, Australia Posts: 1,519 Thanks: 3  Re: Probability practice problems?
You need the generalized hypergeometric formula. If you pick n out of N things, and of those a out of A of the first sort, b out of B of the first sort, etc (so a+b+c+... = n, and A+B+C+... = N) then the probability is In this case you pick 1 white, 1 green, 2 blue, OR 1 white, 2 green, 1 blue, OR 2 white, 1 green, 1 blue. 

Tags 
practice, probability, problems 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Can anyone help me with some practice math test problems?  RaitoMath  Algebra  3  March 14th, 2014 05:10 PM 
Practice Problems  matthematical  Real Analysis  0  October 2nd, 2011 11:42 PM 
Where can I find some trig practice problems?  NeuroFuzzy  Algebra  2  March 13th, 2011 12:27 AM 
Need practice factoring for calculus problems  roncarlston  Calculus  1  February 4th, 2011 03:28 PM 
Basic Maths Practice Problems  coote  Algebra  0  December 31st, 1969 04:00 PM 