Page 217 - Math Course 3 (Book 2)

Probability Distributions

Your Turn!

Random Variable
A survey was conducted concerning the number of Find the probability that a randomly chosen
movies people watch at the theater per month. The person watches at most 1 movie per month.
results of this survey are shown in the table.
A. 30% B. 40%
C. 50% D. 60%
Number of movies Number of people
(per month) Answer
0 7 Find the probability that a randomly chosen
1 23 person watches 0 or 4 movies per month.
2 30 A. 0 % B. 10%
3 29 C. 18% D. 100%
4 11
Answer

MO. 12 - L8b Key Concept

Using Probability Distributions
Properties of Probability Distributions

1. The probability of each value of X is greater
Vocabulary A-Z than or equal to 0 and less than or equal to 1.

Let us learn some vocabulary 2. The probabilities of all the values of X and add
up to 1.

probability distribution
The probability of every possible value of the ran-
dom variable X is called a probability distribution. Let’s Begin

Number of Pets Probability Distribution Table
0 X = number of Pets P(X)
1 0 0.03 Probability Distribution
1
0.37
2 2 0.33
3 3 0.18 Example
4 4 0.09

probability histogram POPULATION
The table shows the probability distribution of the
The probability distribution for a random variable number of students in each grade at Sunnybrook
can be given in a table or in a probability histogram. High School. Show that the distribution is valid.

0.50
0.40 X = Grade P(X)
0.30 9 0.29
P(X) 0.20 10 0.26

0.10 11 0.25
12 0.2
0
0 1 2 3 4
x = number of Pets
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