# What two numbers do you divide to get the probability?

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Mr. McGee is the manager of the washer and dryer department of an appliance store. He wants to estimate the probability that a customer who comes to his department will buy a washer or dryer. He collected the following data during one week: 177 customers came to his department, 88 purchased washers, 64 purchased dryers, and 69 did not make a purchase.

Make a two-way table.

What to numbers do I divide to get the probability that a customer will buy a washer or dryer? I just need to know the numbers that I divide and I can do the rest.

Mr. McGee is the manager of the washer and dryer department of an appliance store. He wants to estimate the probability that a customer who comes to his department will buy a washer or dryer. He collected the following data during one week: 177 customers came to his department, 88 purchased washers, 64 purchased dryers, and 69 did not make a purchase.

Make a two-way table.

What to numbers do I divide to get the probability that a customer will buy a washer or dryer? I just need to know the numbers that I divide and I can do the rest.

##### 1 Answer

#### Explanation:

Note that

This is fairly straightforward, since we know how many did *not* make a purchase. If 69 people didn't make a purchase, then

So our probability is the number of people who made a purchase divided by the total number of people. That is,