The normal distribution N(μ, σ²) has: (1) a bell-shaped, symmetric probability density function; (2) mean μ, median, and mode are equal at the center; (3) approximately 68% of observations lie within μ ± σ, 95% within μ ± 2σ, 99.8% within μ ± 3σ; (4) inflection points occur at μ ± σ.