Page 216 - Math Course 3 (Book 2)

Probability Distributions
Mo. 12

Lesson 8
Let’s Begin

KEY CONCEPTS:
Random Variable
1. Use random variables to compute
probability. Example
2. Use probability distributions to solve
real-world problems.

The owner of a pet store asked customers how
many pets they owned. The results of this survey
MO. 12 - L8a are shown in the table.

Probability Distributions Number of Pets Number of Costumers
0 3
1 37
2 33
Vocabulary A-Z 3 18

Let us learn some vocabulary 4 9

Find the probability that a randomly chosen
random variable customer has at most 2 pets.

A random variable is a variable with a value that is
the numerical outcome of a random event. There are 3 + 37 + 33 or 73 outcomes in which a
customer owns at most 2 pets, and there are 100
survey results.

73
P(X ≤ 2) =
100
The probability that a randomly
Answer chosen customer owns at most 2
discrete random variable pets is or 73%.
73
A discrete random variable has a finite number of 100
possible outcomes. Find the probability that a randomly chosen
customer has 2 or 3 pets.
Number of Pets There are 33 + 18 or 51 outcomes in which a
0 customer owns 2 or 3 pets.
1
2 51
3 P(2 ≤ X ≤ 3) = 100
4
The probability that a randomly
We can let the random variable X represent Answer chosen customer owns 2 or 3 pets
51
the number of pets owned. Thus, X can is or 51%.
100
equal 0, 1, 2, 3, or 4.

208