Stats

Question 1

What is the sum of the probabilities for a discrete random variable?

Answer 1

P (X = x) = 1

Question 2

What is the expected value of a discrete random variable, X?

Answer 2

E (X) = the sum of ( x P (X = x) )

Question 3

What is the expected value of a discrete random variable, X^2?

Answer 3

E (X^2) = the sum of ( x^2 P (X = x) )

Question 4

What is the variance of a discrete random variable, X?

Answer 4

Var (X) = E (X^2) - E(X)^2

Question 5

What are the different formuale that could be used for Expectation and Variance?

Answer 5

E (aX) = a E(X)
E (aX + b) = a E(X) + b
Var (aX) = (a^2)(Var(X))
Var (aX + b) = (a^2)(Var(X))
This is due to the fact if b is added or subtracted from each value the variance of the distribution will be unchanged.