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A shop has a mean wait of five minutes and a standard deviation of two minutes. Rosa waits seven minutes. How far above the mean is that?
ATwo standard deviations
BFive standard deviations
COne standard deviation
DSeven standard deviations
Answer & Solution
Correct answer: C. One standard deviation
1. Start by finding how far the wait is from the mean.
2. Seven minutes minus five minutes is two minutes.
3. Now measure that gap in standard deviations by dividing by two minutes.
4. Two divided by two is one, so Rosa waited one standard deviation above the mean.
_Source: OpenStax High School Statistics (CC BY 4.0), Ch 2 "Descriptive Statistics" and Ch 3 "Probability Topics", section 2.7 Measures of the Spread of the Data_
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