Answer :
Using z-scores, it is found that the unusual values are those that are less than 124.
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The z-score of a measure X in a data-set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex] is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
- The z-score measures how many standard deviations X is from the mean.
- Measures that are more than 2 standard deviations from the mean are unusual.
- Z < -2 means that the measure X is unusually low.
- Z > 2 means that the measure X is unusually high.
In this problem:
- Mean of 150, thus [tex]\mu = 150[/tex].
- Standard deviation of 13, thus [tex]\sigma = 13[/tex].
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]-2 = \frac{X - 150}{13}[/tex]
[tex]X - 150 = -2(13)[/tex]
[tex]X = 124[/tex]
Unusual values are those that are less than 124.
A similar problem is given at https://brainly.com/question/15315313