alleryStart learning →The z-scores that bound the middle 99.7 percent of a normal distribution are:
AMinus 4 and plus 4
BMinus 3 and plus 3
CMinus 2 and plus 2
DMinus 1 and plus 1
Answer & Solution
Correct answer: B. Minus 3 and plus 3
1. Each empirical rule percentage corresponds to a pair of z-scores.
2. The z-scores are minus 1 and plus 1 for one standard deviation.
3. They are minus 2 and plus 2 for two standard deviations.
4. About 99.7 percent lie within three standard deviations, so the bounds are minus 3 and plus 3.
_Source: OpenStax Introductory Statistics 2e (CC BY 4.0), Ch 6 'The Normal Distribution', sections 6.1-6.3_
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