Discrete Random Variables

Question 1

What is a discrete random variable

Answer 1

A variable that can take no more than a countable number of values

Question 2

How to calculate cumulative probabilities as part of cumulative distribution function

Answer 2

Add up the probability of that class and all previous classes

Question 3

How to calculate expected value

Answer 3

Sum of Xp(X)

Question 4

How to calculate E(X^2)

Answer 4

Sum of X^2p(X)

Question 5

How to calculate variance of a random variable

Answer 5

E(X^2) - [E(X)]^2

Question 6

What can you draw with a probability distribution

Answer 6

A histogram

Question 7

How to calculate marginal probabilities

Answer 7

Add up for x ignoring y
Add up for y ignoring x

Question 8

How to calculate covariance of a random variable

Answer 8

E(XY)- E(X) x E(Y)

Question 9

Variance of a random variable

Answer 9

E(X^2) - E(X)^2

Question 10

What is the mean of a disrete uniform distribution

Answer 10

A+B/2

Question 11

What is the variance of a discrete uniform distribution

Answer 11

N^2-1/12