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**Unformatted text preview: **d
deviations above the mean. We don’t know
yet exactly what percent of students would
score more than her, but it’s somewhere
between 16% and 50%. Exam 2: Rachel’s score of 80 is 1 standard
deviation greater than the mean. We know
that approximately 16% of the students
would score less than her. (That is, she’s in
the approximate 84th percentile.) Since fewer students will score higher than her on the second exam compared
to the first exam, her performance on the second exam was better compared
to the rest of the class than on the first exam. Summary
W hich measures of center and spread to use depends on the shape of data. If data are skewed, the median
and quartiles should be reported. If data are symmetric, the mean and median are the same, so either one
can be used to describe the measure of the center. The standard deviation is an ideal measure of spread for
symmetric data. One particular common symmetric shape is the normal curve. The normal curve can be
completely describe...

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