A bag contains five white balls and four black balls. Your goal is to draw two black balls.
You draw two balls at random. What is the probability that they are both black?
+23252 You start with 9 balls, 5 white and 4 black.
To choose a black ball from the 9 balls, there are 4 possible choices: 4/9
Now, there are only 8 balls left, 5 white and 3 black.
To choose a black ball from the 8 balls, there are 3 possible choices: 3/8
The probability that both will occur is: 4/9 x 3/8 = 12/72
