95% of data under a normal distribution curve fall between which z-scores?
A) -1 and +1
B) -2 and +2
C) -2.5 and +2.5
D) -3 and +3

Question

Quizplus · Accepted Answer

According to the empirical rule, approximately 95% of data falls within 2 standard deviations (or 2 z-scores) of the mean. Since the standard deviation of a normal distribution is 1, 2 standard deviations from the mean would be -2 and +2 z-scores. Therefore, 95% of data falls between -2 and +2 z-scores.

95% of Data Under a Normal Distribution Curve Fall Between