Posted by Jenni on .
A box contains two black balls and three gold balls. Two
balls are randomly drawn in succession from the box.
a. If there is no replacement, what is the probability
that both balls are black?
b. If there is replacement before the second draw, what
is the probability that both balls are black?

math 
PsyDAG,
After first draw, there is one less black ball and one less total balls. To find probability of both/all events occurring, multiply the probabilities of the individual events.
a. 2/5 * 1/4 = ?
Probability is the same for both draws.
b. 2/5 * 2/5 = ?