Lesson objective: Practice using addition to find the probabilities of "at least," "or," and "less than" *without replacement.*

This lesson helps to build fluency with using multiplication to find the probabilities of dependent compound events and addition to find the probability of one compound event or another. An equation is used here because it highlights using multiplication to find the probability of each dependent compound event and addition to find the probability of one compound event or another. This work develops students' understanding that probabilities of dependent events have different numbers of possible outcomes for each event and that the outcome of one event affects the outcome of another event.

Students engage in Mathematical Practice 5 (using appropriate tools strategically) as they use equations to find the probability of dependent compound events.

**Key vocabulary:**

- at least
- dependent events
- less than

**Special materials needed:**