Answer:
1/3.
Explanation:
The probability that the red cube WON'T be picked on the first draw is 2/3. This is because there is a 1/3 probability of picking a green cube, added to a 1/3 probability of picking a blue cube.
The probability that the red cube WON'T be picked on the second draw is 1/2. This is because one cube has already been picked, so there are two remaining. You can only pick one of the two.
(2/3) * (1/2) = (2 * 1) / (3 * 2) = 2 / 6 = 1/3.
Hope this helps!