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A z-score of plus 1 marks the value that is:
AOne unit above the mean
BOne percent above the mean
COne deviation above the mean
DOne deviation below the mean
Answer & Solution
Correct answer: C. One deviation above the mean
1. A z-score counts standard deviations rather than original units.
2. The z-scores are minus 1 and plus 1 for the values one deviation either side of the mean.
3. So plus 1 sits exactly one standard deviation above the mean.
4. Minus 1 sits the same distance below it.
_Source: OpenStax Introductory Statistics 2e (CC BY 4.0), Ch 6 'The Normal Distribution', sections 6.1-6.3_
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