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# Practice problems for probability of compound events: video lesson

In this video lesson, I solve several probability problems that involve compound events by listing all the possible outcomes or by drawing a tree diagram. Either way, we have the complete sample space, and we can figure out the probabilities just by writing the ratio of the favorable outcomes to all the possible outcomes (definition of simple probability).

The situations include:

• choosing two students from among five to clean the classroom
• tossing a coin 2 times (there are four possible outcomes)
• tossing a coin 3 times (there are eight possible outcomes)
• picking two cards randomly from a set of cards.

This lesson suits grades 7-8, and meets the Common Core standard 7.SP.8a and 7.SP.8b:

a. Understand that, just as with simple events, the probability of a compound event is the fraction of outcomes in the sample space for which the compound event occurs.
b. Represent sample spaces for compound events using methods such as organized lists, tables and tree diagrams. For an event described in everyday language (e.g., "rolling double sixes"), identify the outcomes in the sample space which compose the event.