CPM Homework Help : INT1 Problem 10-10

In a certain small town, $65$ % of the residents subscribe to the city Sunday paper, 37% subscribe to the weekly local paper, and 25% subscribe to both papers.

What are the two variables? Create a two-way table to represent the data.
Step (a):
Subscribes to
weekly local
paper
Subscribes to Sunday paper
yes
no
yes
$0.25$
$\mathbf{0.37}$
no
$\mathbf{0.65}$
$\mathbf{1.00}$
If a resident is selected at random, what is the probability he or she subscribes to at least one of the two papers?

Hint (b):

Which three boxes in the two-way table represent someone subscribing to at least one paper?

Answer (b):

$25\%+12\%+40\%=77\%$

Charlie’s neighbor subscribes to a paper. What is the probability that he takes the Sunday paper?

Hint (c):

This is the probability of someone subscribing to the Sunday paper given the information that they subscribe to at least one paper.
Use your answer from part (b).

Step (c):

$\frac{65}{77}=?$

Subscribes to weekly local paper	Subscribes to Sunday paper
		yes	no
	yes	$0.25$		$\mathbf{0.37}$
	no
		$\mathbf{0.65}$		$\mathbf{1.00}$