Answer:
a) There is a 15.3% probability that a randomly selected person in this country is 65 or older.
b) Given that a person in this country is uninsured, there is a 2.2% probability that the person is 65 or older.
Step-by-step explanation:
We have these following percentages:
5.3% of those under the age of 18, 12.6% of those ages 18–64, and 1.3% of those 65 and older do not have health insurance.
22.6% of people in the county are under age 18, and 62.1% are ages 18–64.
(a) What is the probability that a randomly selected person in this country is 65 or older?
22.6% are under 18
62.10% are 18-64
The rest are above 65
So
100% - (22.6% + 62.10%) = 15.3%
There is a 15.3% probability that a randomly selected person in this country is 65 or older.
b) Given that a person in this country is uninsured, what is the probability that the person is 65 or older?
This can be formulated as the following problem:
What is the probability of B happening, knowing that A has happened.
It can be calculated by the following formula
Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.
So, what is the probability that a person is 65 and older, given that the person is uninsured.
P(B) is the probability that a person is 65 and older. From a), we have that 
P(A/B) is the probability is uninsured, given that that person is 65 and older. So 
P(A) is the probability that a person is uninsured. That is the sum of 5.3% of 22.6%, 12.6% of 62.1% and 1.3% of 15.3%. So:
So
Given that a person in this country is uninsured, there is a 2.2% probability that the person is 65 or older.
