Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
3. Two-Way Tables and Probability
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Exercise 19 Page 690

Ask easy yes or no questions to make a simple two-way table.

See solution.

Practice makes perfect

We were asked to create and conduct a survey. Since a lot of people have pets, we created a survey about that. We asked each student in the class if they have a dog or a cat. To create a two-way table, we will write the answer to each question as a header. Let's make it!

Has a Dog Does Not Have a Dog
Has a Cat
Does Not Have a Cat
There were 50 students who took our survey. Here are the results.
  • 10 students have a dog and a cat.
  • 12 students have a dog, but do not have a cat.
  • 7 students do not have a dog, but have a cat.
  • 21 students do not have a dog or a cat.

Each of these numbers is a joint frequency. Let's add these values to the table in the appropriate cells.

Has a Dog Does Not Have a Dog
Has a Cat 10 7
Does Not Have a Cat 12 21

Finally, to find the marginal frequencies, we will add the joint frequencies from each row and each column.

Has a Dog Does Not Have a Dog Total
Has a Cat 10 7 10+ 7 = 17
Does Not Have a Cat 12 21 12+ 21 = 33
Total 10+ 12 = 22 7+ 21 = 28 50

Any survey with categorical responses can have the results displayed in a two-way table with joint and marginal frequencies which are found in the same way. This is just one example.