Find the probability andodds of simple events.

The probability of an event—the ratio of the number of favorable outcomes for the event to the total number of possible outcomes.

EXAMPLE: When you flip a coin, there are two possible outcomes. The probability of getting a heads is 1:2 or .

Sample space—list of all possible outcomes. When you roll a die, there are six possible outcomes:

1, 2, 3, 4, 5, or 6.

What is the sample space of spinning this spinner?

• When there are n outcomes and the probability of each one is , we say that the outcomes are equally likely. – For example, when you roll a die, the 6 possible

outcomes are equally likely because each outcome has a probability of .

• The probability of an event is always between 0 and 1, inclusive. The closer a probability is to 1, the more likely it is to occur.

A die is rolled.

Find each probability.a. rolling a 1 or 5

𝟐𝟔𝒐𝒓

𝟏𝟑

b. rolling an even number

A bowl contains 5 red chips, 7 blue chips, 6 yellow chips, and 10 green chips.One chip is randomly drawn. Find each probability.a. blue 1

4

b. red or yellow1128

c. not green914

One method used for counting the number of possible outcomes is to draw a tree diagram. The last column of a tree diagram shows all of

the possible outcomes.

Fundamental Counting Principle

• Assignment: page P36 (front of book) all.