Probability with Random Variables

A random variable is defined by a rule that assigns a _______________ to every outcome in a sample space.

• number

• letter

• Event

• probability

A fair coin is flipped three times. What is the probability of seeing heads exactly once?

• 3/8

• 1/8

• 1/2

• 1/6

The Sum Rule states that the sum of the probabilities of all instances of a random variables equals...

• 1

• 0

• P(E)

• P(E')

Two fair dice are rolled and the numbers that appear are added. What is the probability that this sum is exactly 3?

• 1/12

• 1/18

• 1/4

• 1/6

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.

It is a variable whose values are determined by chance.

• Random Variable

• Discrete Variable

• Continuous Variable

• Independent Variable

What is the numerical quantity assigned to the outcome of an experiment usually denoted by an uppercase letter such as X?

• Frequency

• Probability

• Random variable

• Sample

Which of the following refers to a rule that assigns a numerical value or characteristic to an outcome of an experiment?

• Expected Value

• Random Variable

• Range Space

• Probability Distribution

An instance of a random variable is...

• an entry in a hypothetical list of possible outcomes.

• any phenomenon in which all outcomes are equally likely.

• a number that changes in a predictable way in the long run.

• a number that is associated with a set of outcomes

In a small town of 100 households, 29 own no dogs, 38 own one dog, 22 own two dogs, and 11 own three dogs. Two different households are picked at random. Let "x" = the total number of dogs these two households own. Find P(x>2).

• 0.4244

• 0.4202

• 0.4278

• 0.4235