WEBJan 18, 2024 · The most common confidence level is 95%. In the statistical table find the Z (0.95)-score, i.e., the 97.5th quantile of N (0,1) – in our case, it's 1.959. Compute the standard error as σ/√n = 0.5/√100 = 0.05. Multiply this value by the z-score to obtain the margin of error: 0.05 × 1.959 = 0.098.