Discrete Probability and Expected Values

A discrete random variable X has the probability distributions shown in the table. Find the value of k.

• 1/3

• 7/12

• 1/12

• 1/4

The random variable X has a probability function shown. Find the value of k.

• 0.1

• 0.01

• 10

• 1/9

A discrete random variable has a probability distribution shown in the table. Find the value of a.

• 0.25

• 0.75

• 0.5

• 0.125

A discrete random variable X has the probability distribution shown in the table. Find P(1 < X ≤ 3).

• 7/8

• 1/2

• 5/8

• 3/8

A discrete random variable X has the probability distribution shown in the table. Find P(X < 2).

• 7/8

• 1/2

• 5/8

• 3/8

A discrete random variable X has the probability distribution shown in the table. Find P(X > 3).

• 1

• 7/8

• 1/8

• 0

Given the probability model in the table below, what is the expected value of the random variable?
  X        50          20        5
P(X)     0.1         0.3      0.6

• 14
• 4.67
• 5
• 7.5

Choose an American household at random. What is the expected number of cars for that household?

• 1.75
• 1.84
• 2.00
• 2.50

Is the distribution below a probability distribution? Why or why not?

• Yes. All P(x) values are between 0 and 1, and ∑P(x) = 1
• No, not all P(x) values are between 0 and 1.
• No, ∑P(x) ≠ 1.

Find the expected value of the table shown (you must first find c).

• 1.35

• 0.5

• 0.05

• 2.24