math
posted by gary .
(1) A bag contains 3 red marbles and 5 blue marbles. Jake will choose 2 marbles without looking. What is the probability that he will choose a blue marble followed by a red marble?
(2) Suppose Jake wants to pick a third marble from the set in question 1. He has already picked a blue marble and then a red one . What is the probability that the third marble will be red?

1. Blue = 5/(3+5) = ?
Since blue marble is already gone, red = 3/(3+4) = ?
Probability of all events occurring is found by multiplying the probabilities of the individual events.
2. 2/(2+4) = ?