is the measure of how likely an event is (written as a ratio) Probability is the measure of how likely an event is (written as a ratio)

Probability of an event The number of ways the event can occur divided by the total number of possible outcomes P(A) = The number of ways an event can occur Total number of possible outcomes

Example#1: You roll a six-sided die whose sides are numbered from 1 through 6. a) What is the probability of rolling an ODD number? P(odd) =

P(“t”) = b) What is the probability of rolling a number that starts with the letter “t”? P(“t”) =

Example #2: A jar contains 6 red, 5 green, 8 blue and 3 yellow marbles. P(red) = P(green) = P(blue) = P(yellow) =

Example#2: A jar contains 6 red, 5 green, 8 blue and 3 yellow marbles. P(orange) =

Example #3: A deck of cards contains 52 cards made up of 4 different suits – Hearts, Diamonds, Spades, and Clubs. a) What is the probability of drawing a heart?

b) What is the probability of drawing a 3 b) What is the probability of drawing a 3? c) What is the probability of drawing a face card?

Practice #4 The table gives the handedness and eyedness of a randomly selected group of 100 people. Right-Eyed Left-Eyed Right-Handed 57 31 Left-Handed 6 What is the probability of getting a left-handed person?

Practice #4 The table gives the handedness and eyedness of a randomly selected group of 100 people. Right-Eyed Left-Eyed Right-Handed 57 31 Left-Handed 6 What is the probability of getting someone who is left-eyed?

Practice #4 The table gives the handedness and eyedness of a randomly selected group of 100 people. Right-Eyed Left-Eyed Right-Handed 57 31 Left-Handed 6 What is the probability of getting someone who is left-handed and is also left-eyed?

Practice #4 The table gives the handedness and eyedness of a randomly selected group of 100 people. Right-Eyed Left-Eyed Right-Handed 57 31 Left-Handed 6 What is the probability of getting someone who is right-handed and is also right-eyed?

Practice #5 The chart shows favorite subjects of students based on their gender. Math Science English SS Male 46 42 13 25 Female 12 21 45 36 What is the probability that a randomly chosen student likes Social Studies the most?

Practice #5 The chart shows favorite subjects of students based on their gender. Math Science English SS Male 46 42 13 25 Female 12 21 45 36 What is the probability that a randomly chosen student is female?

Practice #5 The chart shows favorite subjects of students based on their gender. Math Science English SS Male 46 42 13 25 Female 12 21 45 36 What is the probability that a randomly chosen student both likes science and is a male?

Practice #5 The chart shows favorite subjects of students based on their gender. Math Science English SS Male 46 42 13 25 Female 12 21 45 36 d) What is the probability that a randomly chosen student likes social studies and is a female?

Classwork!

Probability Tables

A Little Vocabulary Athletics Music/Arts SGA Other Total Male   Athletics Music/Arts SGA Other Total Male Male total Female Female total Athletics total Music/arts total SGA total Other total Table total

Joint Probability

Marginal Probability

Conditional Probability

Example 1 Using the table below, what is the joint probability of a female that is involved in SGA? 0/30 = 0%   Athletics Music/Arts SGA Other Total Male 10 5 1 2 18 Female 6 12 15 11 3 30

Example 2 Using the table below, what is the marginal probability of choosing someone who is involved with athletics? 15/30 = 50%   Athletics Music/Arts SGA Other Total Male 10 5 1 2 18 Female 6 12 15 11 3 30

Example 3 Using the table below, what is the conditional probability given that a person is male, that they are involved in Music/Arts? 5/18 = 28%   Athletics Music/Arts SGA Other Total Male 10 5 1 2 18 Female 6 12 15 11 3 30

Classwork Task Handout

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