3. Discrete Random Variables

Variance And Sd — Quiz

Test your understanding of variance and sd with 5 practice questions.

Practice Questions

Question 1

A discrete random variable $X$ takes values $1, 3, 5$ with probabilities $0.2, 0.5, 0.3$. What is the variance of $X?

Question 2

If the values of a discrete random variable $X$ are all multiplied by $3$, how does the variance change?

Question 3

A discrete random variable $X$ takes values $2, 4, 6$ with probabilities $0.3, 0.4, 0.3. What is the standard deviation of $X$?

Question 4

Which of the following best describes the meaning of a large standard deviation in a discrete random variable?

Question 5

A discrete random variable $Y$ takes values $0, 2, 4, 6$ with probabilities $0.1, 0.2, 0.4, 0.3$. What is the variance of $Y?