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Mathematics

68-95-99.7 Rule (Empirical Rule)

Quick fact

The 68-95-99.7 rule applies only to data that follows a perfectly normal distribution, which appears often in nature—from heights to test scores to measurement errors.

Why this is interesting

Have you ever wondered how often a measurement falls close to the average? In a perfect bell curve, almost all data hugs the center in a predictable pattern—but how tightly?