What are two other names for the empirical rule?

• A. The 60-70-80 rule
• B. 68-95-99.7 and the three-sigma rule
• C. The 50-60-70 rule
• D. The 65-75-85 rule

Answer: (B)

The main idea here is recognizing the two common labels for the empirical rule, which describes how data in a normal distribution tend to cluster around the mean. The rule states that about 68% of values lie within one standard deviation, about 95% within two, and about 99.7% within three. One of its well-known names emphasizes those exact percentages and is often called the sixty-eight–ninety-five–ninety-nine point seven rule. The other name highlights the distance from the mean in terms of standard deviations and is called the three-sigma rule. These two labels are widely used to refer to the same concept. The other options don’t match these recognized names and describe incorrect or nonstandard phrasing for the empirical rule.