Section 1Probability and Odds

Vocabulary

probability: how likely it is an event will occur

experiment: taking a measurement or making an observation

experimental probability: probability determined by observation or measurement

outcome: result of each trial of an experiment

Experimental Probability

number of favorable observations of ( )total number of observations

EP E

• Probability is between 0 and 1.

• If probability is 0 then it is IMPOSSIBLE for the event to occur

• If probability equals 1 then the event is CERTAIN to occur

Ex 1

• Find the probability of rolling a number greater than two on a die

Ex 2• A class contains 6 students with black

hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find P(black)

• Find P(red or brown)

• Find P(not blonde)

Ex 3Lions fans

attending a recent 3-game series were asked whether the team should have a mascot. The table shows the results of the survey.

What is the probability that a Lions’ fan wants a mascot?

GameGame AttendancAttendancee

In favor In favor of of

mascotmascot

Friday 681 388Saturday 527 428Sunday 928 786

Ex 4A softball player has had 24

hits in her first 60 times at bat. Predict her number of hits in 330 at bats.

theoretical probability: the ratio of favorable outcomes to the number of possible outcomes in a sample space

number of favorable outcomes( )number of possible outcomes

P T

Experimental probability approaches theoretical probability as more trials are performed in an experiment.

Ex 5A card is picked at random from a standard

deck of 52 cards. Find P(face card).

Find P(#7)

Standard Card Deck• 52 cards total• 2 colors (red, black)• 4 suits (hearts, diamonds, spades, clubs)• 13 cards per suit (A,2,3,4,5,6,7,8,9,10,J,Q,K)• 3 face cards per suit (J, Q, K)

odds: the ratio of favorable outcomes to the number of unfavorable outcomes

number of favorable outcomes( )number of unfavorable outcomes

O T

Ex 5What are the

odds of rolling a 4 on a standard number cube?

Ex 6What are the odds of rolling a 4 on a

standard number cube?

Find the odds of rolling a number greater than two.

What are the odds of rolling not a 2 or 3?

Ex 7

• A card is selected at random from a standard deck of 52 cards. What are the odds against selecting a 2 or a 3?