How to Find Probabilities Using Frequency Tables

Contributor: Lynn Ellis. Lesson ID: 13774

Have you ever wanted to organize information about categorical variables into a frequency table and use that table to find probabilities of specific events? Of course you have! Learn how here.

categories

Measurement and Data, Statistics and Probability

subject
Math
learning style
Auditory
personality style
Beaver
Grade Level
High School (9-12)
Lesson Type
Quick Query

Lesson Plan - Get It!

Audio:

family reunion

You are at a family reunion with 50 of your relatives from all over the country. Everyone in your family has either brown eyes or blue eyes. Some wear glasses, and some do not.

  • How can you find the probability that a member of your family has blue eyes and wears glasses?

One of the best ways to find a probability in a situation like this is with a two-way frequency table.

To see how a two-way frequency table is constructed and how you can use it to find probabilities, watch Two Way Frequency Tables from Lynn Ellis:

You can see from the video that, in order to find the probability that a person in your family has blue eyes and wears glasses, you can create a two-way frequency table.

In the video example, the probability of having blue eyes and wearing glasses is 12/50 or 24%.

Try applying what you learned in the video by making your own two-way frequency table. You may draw your own or use the Two-Way Frequency Table Templates found under the Downloadable Resources in the right-hand sidebar.

Use the following information to create your table:

You want to know which treat people prefer for their birthdays: pie or cake. You ask 50 people; some adults and some children. 16 adults prefer pie, and 3 children prefer pie. On the other hand, 18 children prefer cake while 13 adults prefer cake.

  • Were you able to complete your table?

Check your answers below before you move on.

 pencil erasing

Correct any mistakes on your table before moving on to the Got It? section, where you will use it to find probabilities.

Elephango's Philosophy

We help prepare learners for a future that cannot yet be defined. They must be ready for change, willing to learn and able to think critically. Elephango is designed to create lifelong learners who are ready for that rapidly changing future.