Exercises: Fitting Data to a Normal Distribution

Work through each section in order. For empirical-rule problems, use the 68-95-99.7 percentages and the curve's symmetry. For z-score problems, first standardize with $z = \frac{x - \text{mean}}{\text{SD}}$, then look up the area with a calculator, spreadsheet, or table. Round percentages as directed. Remember: the empirical rule and z-scores apply ONLY to roughly normal data.