Two standard deviations about the mean of a normal distribution include approximately ____ of all observations.
A)90%
B)95%
C)99%
D)Can't say;it depends on the individual sample variance.
E)Can't say;it depends on the size of the population.

Question

Quizplus · Accepted Answer

The Empirical Rule states that for a normal distribution, approximately 95% of all observations will fall within two standard deviations of the mean. Therefore, choice B is the best answer.

Two Standard Deviations About the Mean of a Normal Distribution