7th Grade Math: Probability Problems

How to Practice Probability at Home

Probability is the likelihood that an event will occur. In school, your 7th grader will learn to collect data to calculate the probability of an event. Reinforce this at home by conducting your own probability experiments.

For instance, if you have different colored cups at home, ask your child to calculate the probability that he'll grab a blue one. This can be a fun way to review probability while setting the table for dinner. Another classic example of probability is a coin toss. Make it into a game by trying to guess which side it will land on.

If your child plays baseball, she can calculate the probability that she and her teammates will hit the ball. After collecting data through observation for a few weeks, she can create a table for the data and find the average times the ball was hit out of the total times that each player was at bat.

Sample Probability Problems and Solutions

1. There's an icy spot on the sidewalk. Seven out of fifteen people slipped while walking over it. What's the probability that the next person will also slip?

Probability is calculated by dividing the frequency of a specific event (e.g., slipping on the ice) by the total times that an event occurred (e.g., people walking over the icy spot). For this problem, divide 7/15, which equals about 0.4667. Multiply the decimal by 100 to find out the percentage. There's a 46.67% chance that the next person will fall while walking over the icy sidewalk.

2. Jeanne's dog barks almost every time another dog walks by. For the last fifteen minutes, 16 dogs have passed and she's barked at 11 of them. What's the likelihood that she'll bark at the next dog?

Out of a total of 16 dogs, only 11 were barked at, so the calculation should look like this: 11/16 = 0.6875. So, there's a 68.75% chance that she'll bark at the next dog.

3. You forgot to do the homework for class and the teacher is calling on students to review the answers! If there are 34 students in the class, what's the probability that you'll be called on next?

There's a 1 in 34 chance that you'll be called on, which is about 0.0294 or 2.94%.