Since it's either/or, we can simply add up 3/10 (0.3) and 1/5 (0.2) to get 0.5=1/2
Solution:
For the first marble chosen by the player1,
The probability that the marble is red is 3/9=1/3
After that the second player chose without replacement, there are 8 marbles left, of which 6 are blue. So the probability of the second one being red is 6/8 = 3/4.
Since the question is asking the probability of both events happening,
So we have to multiply the two probabilities.
So the answer is (1/3) * (3/4) = 1/4.
