Page 90 - Algebra 1

Example
1
Identifying Sample Spaces
A number cube labeled 1–6 is rolled. List the outcomes for each event.
a. a number less than or equal to 3 SOLUTION
{3, 2, 1}
c. a number greater than 4 SOLUTION
{5, 6}
b. an odd number SOLUTION
{1, 3, 5}
Math Language
A spinner is divided into four equal parts: blue, yellow, green, and red. If the spinner lands on yellow, then the outcome is yellow.
Theoretical probability can be determined using the following formula:
P(event) = number of favorable outcomes ___
total number of outcomes
A complement of an event is a set of all outcomes of an experiment that are not in a given event. For example, if heads is the desired event when tossing a coin, tails is the complement of the event. The sum of an event and its complement equals 1.
P(event) + P(not event) = 1 P(not event) = 1 - P(event)
Calculating Theoretical Probability
There are 4 green, 3 blue, and 3 red marbles in a bag. Give each answer as a decimal and as a percent.
Reading Math
The probability of an event can be written P(event). The probability of picking a red marble can be written P(red).
Example
2
a. What is the probability of randomly choosing a red marble? SOLUTION
Hint
Probability can be expressed as a fraction, decimal, or percent.
P(red) = 3 red marbles __
10 marbles in all
P(red) = _3 10
The probability of choosing a red marble is 0.3 or 30%.
b. What is the probability of randomly choosing a marble that is not green?
SOLUTION
P(green marble) + P(not green marble) = 1
P(not green marble) = 1 - P(green marble)
P(not green marble) = 1 - _4 10
P(notgreenmarble)=_6 =_3 10 5
The probability of not choosing a green marble is 0.6 or 60%.
Lesson 14 75