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Probability of either spin

Probability of spinning a number at least once in two tries

This math skill teaches how to calculate the probability of spinning a specific number at least once over two independent tries using a spinner. It involves adding the probabilities of individual events and subtracting the probability of both events happening together.

Learn probability of either spin

Teaching Transcript

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What is the chance of spinning a 5 given two spins?

These are independent events since the spinner doesn't change, and we need either to happen, so the probability of both is the union of the probability of 5, and the probability of 5 again.

For unions, we add the probabilities, and then subtract the intersection, so we have the probability of 5, plus the probability of 5, minus the probability of 5 times itself.

Since there is a single 5, and 6 outcomes, the chance of spinning a 5 is 1 in 6.

So our answer is 11 in 36 as the chance of spinning 5 given two tries.

11 in 36 is zero point three zero five five, or about a 30.5 percent chance.

Skill Practice

Probability of spinning a number at least once in two tries

Test your understanding of probability of either spin by practicing it! Work through the below exercises to use it in practice.