4537. There are 3 white and 6 black balls in the urn.
a) Two balls are taken out of the urn at the same time. Find the probability that they are the same color
b) What event, provided that two balls are taken out of the urn at the same time, is more likely: A - balls of the same color, B - balls of different colors?

Detailed solution. Decorated in Microsoft Word 2003 (Quest decided to use the formula editor)