Posted by Kristen on .
A box contains 20 red balls and 40 green balls . Four balls are randomly selected from the box without replacement. What is the probability of selecting a red ball followed by a green ball and then another red ball followed by a green ball?

Math 
Reiny,
so you want the specific order, RGRG
prob(of that order)
= (20/60)(40/59)(19/58)(39/57)
= 260/5133 reduced to lowest terms
or
= appr .05065