4.3 Given the following contingency table:

B B’

A 10 20

A’ 20 40

What is the probability of

a. event A?

b. event A’?

c. event A and B?

d. event A or B?

4.9 Referring to the contingency table in Problem 4.8, if a respondent is selected at random, what is the probability

that he or she

a. thinks the tax code is unfair?

b. thinks the tax code is unfair and makes less than $50,000?

c. thinks the tax code is unfair or makes less than $50,000?

d. Explain the difference in the results in (b) and (c).

Contingency table:

U.S. TAX

CODE Less Than $50,000 More Than $50,000 Total

Fair 225 180 405

Unfair 280 320 600

Total 505 500 1,005