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A normal distribution has mean 50 and standard deviation 6. Which value carries a z-score of negative 1.5?
AThe value is 59
BThe value is 44
CThe value is 41
DThe value is 35
Answer & Solution
Correct answer: C. The value is 41
1. Rearranged, the value equals the mean plus the z-score times the standard deviation.
2. Here that is 50 plus negative 1.5 times 6.
3. Negative 1.5 times 6 is negative 9.
4. So the value is 50 minus 9, which is 41.
5. Answering 59 adds the 9 instead of subtracting it and lands above the mean.
_Source: OpenStax High School Statistics (CC BY 4.0), Ch 6 "The Normal Distribution", section 6.1 The Standard Normal Distribution_