Probability Trees

Question 1

Expected value for a discrete random variable ?

Answer 1

E(X)= Sum P(Xi)Xi

Question 2

Variance of Xi?

Answer 2

VAR(X)=Sum P(Xi)[Xi-E(X)]2

Question 3

Expected value of a random variable given a scenario s?

Answer 3

E(X|S)=P(X1|S)X1+…+P(Xn|S)Xn

Question 4

Total Probability Rule for Expected Value?

Answer 4

E(X)= E(X|S)P(S)+E(X|Sc)P(Sc)

Question 5

Bayes Formula?

Answer 5

P(Event|Information)=(P(Information|Event)/P(Information))*P(Event)