The following relative frequency distribution describes the household incomes for families living in a suburban community:
|
Income
|
Relative Frequency
|
|
Less than $20,000
|
0.10
|
|
$25,000-under $40,000
|
0.20
|
|
$40,000-under $60,000
|
0.30
|
|
$60,000-under $80,000
|
0.25
|
|
$80,000 or more
|
0.15
|
a. For a randomly selected household, what is the probability that its annual income is less than $80,000?
b. If a household is known to have an income of at least $20,000, what is the probability that its annual income is in the $60,000-under $80,000 category?
c. Two households are randomly selected from those whose income is at least $40,000 per year. What is the probability that both of these households are in the $80,000 or more category?