A bag contains 3 red marbles, 4 blue marbles, and 5 white marbles. What is the probability of pulling out two red marbles in a row if none are replaced?

A. 1/22
B. 1/16
C. 1/24
D. 1/5

"none" is singular.

There are 12 marbles in all, so

P(red,red) = 3/12 * 2/11

To find the probability of pulling out two red marbles in a row without replacement, we need to calculate the probability of pulling a red marble on the first draw, and then the probability of pulling another red marble on the second draw.

First, let's find the probability of pulling a red marble on the first draw. There are a total of 12 marbles in the bag (3 red, 4 blue, and 5 white). So the probability of picking a red marble on the first draw is 3/12.

Now, after we've removed one red marble from the bag, there are only 11 marbles left. Since we want to pull out another red marble, we need to consider how many red marbles are left in relation to the total number of marbles left. There are now only 2 red marbles left in the bag, and the total number of marbles remaining is 11. Therefore, the probability of picking a red marble on the second draw is 2/11.

To find the probability of both events happening, we multiply the probabilities together:
(3/12) * (2/11) = 6/132 = 1/22

Therefore, the probability of pulling out two red marbles in a row without replacement is 1/22.

So, the correct option is A. 1/22.