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Probability of multiple flips

Probability of flipping a coin heads or tails at least once in two tries

This math skill teaches how to calculate the probability of getting tails at least once when flipping a coin two times. It uses the concept of independent events and the formula for the union of probabilities, which involves adding individual probabilities and subtracting their intersection.

Learn probability of multiple flips

Teaching Transcript

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What is the chance of flipping tails at least once, given two tries?

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

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

Obviously the chance of tails is just 1 in 2

So our answer is 3 in 4 as the chance of flipping tails given two tries.

3 in 4 is point seven five, or a 75 percent chance.

Skill Practice

Probability of flipping a coin heads or tails at least once in two tries

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