Gizmo of the Week: Independent and Dependent Events

When calculating the probability of a series of events, it is critical to know if one result affects the probability of another. If you are flipping a fair coin, the probability of heads is 0.5 no matter how many heads or tails have occurred before. If you are playing cards, the probability of drawing an ace from the deck depends on how many aces have been drawn before.

This distinction is the focus of the Independent and Dependent Events Gizmo. In the Gizmo, colored marbles are drawn from a bag. The marbles are either replaced after each draw (independent events) or not replaced (dependent events). Students will learn how to calculate the probability of each outcome in the simple, independent events case, then see how this calculation is changed for the dependent case. As with many probability examples, this would be a great activity to model in the classroom!

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