Posted by F0reveryoung on Saturday, April 7, 2012 at 1:59pm.
An urn has fifteen red balls and nineteen white balls. Three balls are selected at random and the number of red balls are observed.
Find the probability distribution for
Number of Red Balls:
0 =
1 =
2 =
3 =

Probability Distribution  Priscilla, Saturday, April 7, 2012 at 2:41pm
total amount of balls = 15 red + 19 white = 34 balls
0  0/34 = 0
1  1/34
2  2/34 = 1/17
3  3/34 
Probability Distribution  Reiny, Saturday, April 7, 2012 at 2:43pm
Prob red = 15/34
prob white = 19/34
when picking three:
prob(0 red) = C(3,0) (19/34)(18/33)(17/32) = 57/352
prob(1 red) = C(3,1) (15/34)(19/33)(18/32) = 2565/5984
prob(2red) = C(3,2) (15/34)(14/33)(19/32) = 1998/5984
prob (3red) = C(3,3)(15/34)(14/33)(13/32) = 455/5984
notice that the sum of the 4 fractions above is 5984/5984 = 1 
typo  Probability Distribution  Reiny, Saturday, April 7, 2012 at 2:44pm
the 2nd last prob calculation should be 1995/5984