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:
CODE Less Than $50,000 More Than $50,000 Total
Fair 225 180 405
Unfair 280 320 600
Total 505 500 1,005