Finding P(X = 3) for 5 Coin Flips

Algebra 2 · Axiom Academy

EXAMPLE Finding P(X = 3) for 5 Coin Flips Using the binomial probability formula to find the chance of exactly 3 heads in 5 flips A fair coin is flipped 5 times. What is the probability of getting exactly 3 heads? Great work — you used the binomial probability formula to solve a real probability problem. Remember: The binomial formula applies when: there's a fixed number of independent trials, each with the same two possible outcomes and a constant probability of success. Identify the parameters first: n (trials), k (successes wanted), and p (probability of success) — every binomial problem starts here. counts arrangements: it's how many different orders the k successes can occur in among the n trials — here . The answer: , a chance — a little under 1 in 3. This same method — identify n , k , p , then plug into — works for any binomial probability problem.

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