Solution
Sixty Heads
Show the problem again
A fair coin is flipped 100 times. Using a normal approximation with continuity correction, approximately what is the probability of getting 60 or more heads? Answer as a percentage rounded to one decimal place.
Worked solution
The answer is ≈ 2.9% (z = 1.9). The heads count is approximately Normal with mean 50 and standard deviation √(100 · 0.25) = 5. With continuity correction, P(X ≥ 60) ≈ P(Z ≥ (59.5 − 50)/5) = P(Z ≥ 1.9) ≈ 0.0287. The exact binomial answer is 0.0284, so the approximation is excellent, and the result shows 60 heads is genuinely surprising evidence against fairness.
Source: Standard binomial hypothesis-testing exercise from introductory statistics texts. Statement written for AxiomIQ.