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?