Warm up

1. What is the probability of choosing a red card from

a standard deck of cards?

2. What is the probability of choosing a king from a

deck of cards?

3. Given that a card is black, what is the probability

that you choose a 4?

50%

8%

2/26 = 8%

Review HW

Probability Tables

A Little Vocabulary

  AthleticsMusic/Arts SGA Other Total

Male   Male total

Female Female total

Total Athletics total

Music/arts total

SGA total Other total

Table total

Joint Probability

individual celltable total

Marginal Probability

column or row totaltable total

Conditional Probability

individual cellspecified row or column

Example 1Using the table below, what is the joint probability of a female that is involved in SGA?

  Athletics Music/Arts

SGA Other Total

Male 10 5 1 2 18

Female 5 6 0 1 12

Total 15 11 1 3 30

0/30 = 0%

Example 2Using the table below, what is the marginal probability of choosing someone who is involved with athletics?

  Athletics Music/Arts

SGA Other Total

Male 10 5 1 2 18

Female 5 6 0 1 12

Total 15 11 1 3 30

15/30 = 50%

Example 3Using the table below, what is the conditional probability given that a person is male, that they are involved in Music/Arts?

  Athletics Music/Arts

SGA Other Total

Male 10 5 1 2 18

Female 5 6 0 1 12

Total 15 11 1 3 30

5/18 = 28%

Task – Public Opinions

Homework

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