Question

what must be known about a data set before the empirical rule can be used?

choose the correct answer below.

a. approximately 68% of the data must lie within one standard deviation of the mean.
b. the mean must be a known value.
c. the sample size must be at least 100.
d. the distribution must be approximately symmetric and bell - shaped.

Explanation:

The Empirical Rule, also known as the 68 - 95 - 99.7 rule, applies only to approximately symmetric and bell - shaped (normal) distributions. Knowing the mean is not sufficient on its own, and the 68% within one standard deviation is a result of the rule, not a pre - condition. Also, there is no requirement that the sample size be at least 100.

Answer:

D. The distribution must be approximately symmetric and bell - shaped.