Lesson objective: Apply probabilities of compound events to a real-world situation.

This lesson provides an opportunity for students to apply their knowledge and understanding of probability of compound events to a real-life situation. Students are asked to find the probability that two friends will sit across from each other given that there are four seats available with only two that are across from each other.

Key Concept students will use:

- The probability of a compound event is the fraction that represents the number of favorable outcomes of the total number of possible outcomes.

Skills students will use:

- Creating a tree diagram
- Finding the probability of a compound event

Students engage in Mathematical Practice 5 (use appropriate tools strategically) as they choose a tool to model the situation. Some students may use a tree diagram to show all the possible outcomes. Other students may try to use an equation to model the situation.

**Key vocabulary: **

- dependent
- experimental probability
- independent
- theoretical probability

**Special materials needed:**

- calculator