Please answer all three!

P(A or B ) = P(A) + P(B) if A and B are disjoint events. True False D Question 6 2 pts If N (the size of the whole population) is unknown but the probability is given, the formula of the variance is _ (x; - u) P (x) where u is the mean. True O False D Question 7 2 pts P(A|B) means the probability of event B given that event A happened first. True False