# Creating a joint probability table

#### elementarystat

##### New Member
I need help figuring out how to create this joint probability table

43 million people in the United States go without health insurance. Sample data representative of the national health insurance coverage is:

18 to 34: Yes: 750 No: 170
35 and older: Yes: 950 No: 130

My question isn't so much how to make that table, but whether or not to use the 43 million as the denominator. For example, to find 18 to 34, Yes, would it be 750/43 million? It must be because it's the only information provided. Yet, it doesn't make sense to me since the 43 million is everyone Without insurance. Anyone understand this?

#### elementarystat

##### New Member
I think I just figured it out. You have to add up all of the numbers from the table. It would be 750 + 950 + 170 + 130 = 2,000 Not 43 million

#### elementarystat

##### New Member
Question.

One of the questions for this problem asks:

If the individual does not have health insurance, what is the probability that the individual is in the 18 to 34 age group?

I"m not sure how to solve this one. Anyone know?