Peter is giving marbles to some children at a carnival. he has 5 red marbles, 4 blue marbles, and 3 yellow marbles. if peter selects a marble randomly without looking, what is the probability that he will give a blue marble to the first child and then a yellow marble to the second child?

For the first event to occur, we do 

#of blue marbles/total = 4/12 or 1/3

Since this is a situation without replacement, meaning the marble is not put back after the first pick, we must subtract 1 from the total when finding the second event's probability

So for the second event..

#of yellow marbles/ total-1 = 3/11

To find the probability of these two events occurring together, we multiply them together

1/3 x 3/11 = 3/33 = 1/11