Get At Least 1 Head in 4 Coin Flips

Model guide

Why this probability model fits

This is a binomial probability problem because the flips are independent repeated trials with the same success probability, and the question asks for a success-count range.

Setup: This is the same repeated-trial setup as other coin-flip problems, but now you add all valid head counts from 1 through 4.

Replacement: Replacement is not part of the setup. This is not a draw-without-replacement problem.

Independence: Independence still matters because each flip keeps the same p = 0.5.

Worked solution

93.75%

The probability of at least 1 success is 93.75%.

1. Identify this as repeated independent trials with the same success probability.
2. Use P(X in range) = sum of C(n, k)p^k(1-p)^(n-k) terms.
3. Set n = 4, target successes = 1, and p = 0.5.
4. Evaluate the required binomial terms for the requested success range.
5. The final probability is 15/16, which is 93.75%.