My Math Forum  

Go Back   My Math Forum > College Math Forum > Advanced Statistics

Advanced Statistics Advanced Probability and Statistics Math Forum


Reply
 
LinkBack Thread Tools Display Modes
March 23rd, 2012, 07:27 AM   #1
Newbie
 
Joined: Mar 2012

Posts: 1
Thanks: 0

hello conceptual probability questions

hello new to here.

I encounter a problem on probability and then I find out this forum on search engine. It's nice

The problem is

There are 3 blue ball and 1 red ball in a bag, one of the balls are drawn to another bag that contains 4 green ball.
Then two balls are drawn successively from the bag with 4 green ball + one unknown colour ball (without replacement)
What is the probability of getting two balls of the same colour.

I thought there were 4 possiblities. GGGB, GGGB, GGGB and GGGR (G: Green B:Blue R:Red)
for each possibe situation
I set up a formula (3/4) x (2/3)
then for four possible situation, I then sum up to get (3/4) x (2/3) + (3/4) x (2/3) + (3/4) x (2/3) + (3/4) x (2/3)
but the result is undoubtedly wrong because it's bigger than 1 which is impossible.

then the only solution is (3/4) x (2/3) from my guess.

But why..... Why I don't need to split into 4 situation?
kenny1999 is offline  
 
March 23rd, 2012, 03:36 PM   #2
Global Moderator
 
Joined: May 2007

Posts: 6,806
Thanks: 716

Re: hello conceptual probability questions

The straightforward approach is as follows. To get 2 balls of the same color, they both must be green. The probability that the first ball is green is 4/5. Assuming the first ball is green, the probability the second ball is green is 3/4. Therefore the probability that both are green is 4/5 x 3/4 = 3/5.
mathman is offline  
Reply

  My Math Forum > College Math Forum > Advanced Statistics

Tags
conceptual, probability, questions



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
database, conceptual planning, implementation, E-R diagram ungeheuer Applied Math 0 February 26th, 2014 05:41 AM
A conceptual problem in Permutation guru123 Algebra 3 August 26th, 2013 06:57 AM
Conceptual real world math problem. Balls in Bags dragonaut Algebra 0 March 27th, 2013 12:46 PM
Newton's Law (conceptual problem)... nicoleb Calculus 7 November 12th, 2012 11:01 AM
How do I solve this conceptual integral problem? LastXdeth Calculus 4 February 13th, 2012 07:43 PM





Copyright © 2019 My Math Forum. All rights reserved.