There are four balls in a hat: a blue one, a white one, and two red ones. Now I draw simultaneously two balls, look at them, and announce that at least one of them is red.
What is the chance that the other is red as well?
Provided that your statement is truthful, there are five combinations where a red ball is drawn, but only one of these five combinations include two red balls.
Thus the probability is 1 in 5, or 20%.

Posted by hoodat
on 20170519 23:10:27 