True or False. If false, be sure to include why it is false!

1. If either A or B must occur they are called mutually exclusive.
2. If P(A) = 0.4 and the P(B) = 0.5, then A and B must be collectively exhaustive.
3. Suppose A and B are events where P(A) = 0.4, P(B) = 0.5, and P(A and B) = 0.1. Then P(A|B) = 0.4