2.3 Conditional Probability

Question 1

Probability of an event and sum of all probabilites

Answer 1

0 <= P(E) <= 1

S={e1, …, en} then P(e1) + P(e2) + … + P(en) = 1

Question 2

P(E⋃F) when E and F are disjoint vs not disjoint

Answer 2

disjoint: P(E∪F) = P (E)+P (F)

not disjoint: P(E ∪F) = P(E) + P(F)−P(E ∩F)

Question 3

P(E’)

Answer 3

probability of complement = one minus probability of event

P(E’) = 1−P(E)