If you take two balls randomly out of a jar of colored balls, there is a 50% chance that the balls will both be red.

What is the total percentage of red balls in the jar?

The real answer is that the total percentage of red balls in the jar varies discretly from 3/4 (if the total number of balls is 4) to 1/sqrt(2) (if the total number of balls aproaches infinity).

Charlie gave a few possible values in his post.

This would have been a nice problem if the question had been "What is the smallest interval for the possible percentages of red balls?".

Answer; (1/sqrt(2), 3/4 ], or about 70.7 to 75.0 %.

And by the way, if the first ball is put back in the jar befor the second one is drawn, then there is a unique solution, and it is 1/sqrt(2).

Edited on March 4, 2005, 7:55 pm

Posted by ajosin on 2005-03-04 19:53:25