math/probability
posted by KiKi .
A bag contains 7 red chips and 10 blue chips. Two chips are selected randomly without replacement from the bag. What is the probability that both chips are red?

Once the first red chip has been picked, there are only 16 total chips and 6 red chips remaining.
To find the probability that both (all) events occur, you need to multiply the probabilities of the individual events.
7/17 * 6/16 = ? 
A box contains 25 yellow, 28 green and 38 red jelly beans.
If 13 jelly beans are selected at random, what is the probability that:
a) 5 are yellow?
b) 5 are yellow and 7 are green?
c) At least one is yellow? 
the anwser is 4