sasha has 5 red pens and 4 blue pens in her bag. she will randomly pick one pen, keep it, and then randomly pick a second pen. What is the probability that she will pick two blue pens

Answer 1

There are nine pens altogether, out of which 4 are blue.
So the probability of picking a blue the first time is P(B)=4/9.
Now that there are only 3 blue out of 8 left, so the probability of picking a second blue out of P(B)=8 is 3/8.
For both events to happen, we apply the multiplication rule to get
P(BB)=(4/9)*(3/8)