Abag has 4 green marbles, 3 red marbles, and 3 yellow marbles. what is the probability that you pick. a red marble, do not replace it, and pick another red marble?

Total marbles = 4 + 3 + 3 = 10 

Chance of picking a red marble on first pick : 3/10 
Chance of picking a red marble on second pick: 2/9 

Therefore probability = 3/10 * 2/9 = 6/90 = 2/30 = 1/15 

b) 1/15

The bag has a total of 10 marbles. For the first pick, the probability of getting a red is 3/10 as there are only 3 red out of the 10 marbles. For the second, there are only 2 red and 9 total number of marbles. The probability of picking red is 2/9. The final probability asked is the product of these probabilities which is equal to 1/15.