## Lesson: Probability

Developing the Concept

Many problem-solving situations involve using probability. We can use probability to make predictions about events if we have data to analyze. Present the following problem to the class. Roll two 1-6 number cubes and find the sum of the two numbers. Roll again and find the product of the two numbers. Which roll has the greatest probability of getting an odd number for an answer, the roll with the sum or the roll with the product?

- If Ramona chooses a CD at random, what is the probability it has 50-54 minutes of music? ( = )
- If Ramona chooses a CD at random, what is the probability it has less than 55 minutes of music? ( = )
- If Ramona buys a new music CD, is it likely or unlikely to have at least 55 minutes of music? (likely)

**Wrap-Up and Assessment Hints**

Practice mental math probability activities with your students to strengthen their skills in probability and in fractions. For example, have them suppose they are choosing colored cubes or marbles from a bag. A bag contains 2 yellow, 3 black, 3 red, and 4 green marbles. Ask students questions that will lead them to find probabilities: What is the probability of choosing a red marble? ( = ) a green marble? = ) a black or a yellow marble? (). Such activities will provide students with practice simplifying fractions and strengthen students' understanding of probability.