3. Discrete Random Variables

Expectation — Quiz

Test your understanding of expectation with 5 practice questions.

Practice Questions

Question 1

Let X be a discrete random variable with P(X=k)=k/10 for k=1,2,3,4. What is E(X)?

Question 2

Suppose you roll a fair six-sided die to obtain N, then flip N fair coins. Let X be the total number of heads observed. What is E(X)?

Question 3

You have two coins: Coin A is fair (P(heads)=0.5) and Coin B is biased (P(heads)=0.8). You select one coin at random with P(A)=0.4 and P(B)=0.6, then flip it 5 times. Let X be the number of heads. What is E(X)?

Question 4

Let N be uniformly distributed on \\{1,2,3,4,5\\}. Given N, you roll a fair six-sided die N times and let X be the sum of the outcomes. What is E(X)?

Question 5

Using the same distribution as in Question 1 (P(X=k)=k/10 for k=1,2,3,4), what is E(X^2)?