Suppose an urn contains 8 red and 4 white balls. Draw two balls without replacement. What is the probability that both are red?

Suppose a jar contains 18 red marbles and 13 blue marbles. If you reach in the jar and pull out 2 marbles at random at the same time, find the probability that both are red.

Two marbles are drawn from a bag that is 3 red, 4 purple, and 2 black. Find the probability that you picked Atleast one purple. You must draw the tree diagram.

An urn contains 5 green, 6 blue, and 4 red balls. You take 3 balls out of the urn, one after the other, without replacement. Compute the probability that the third ball is red given that the first two balls are green.