A professor's final exam has a mean of 60 and a standard deviation of 12. She decides that it was too difficult, so she adds 15 points to each student's score. Rather than recalculate the mean and standard deviation for the 442 scores, she remembers that she can use the linear transformation rules to recalculate the mean and standard deviation. What are the revised mean and standard deviation of her final exam?

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Answer 1 · 2015-02-07T15:47:14

#mu=75# and #sigma=12#

If she adds 15 points to every score then the mean will also go up by 15 points.

But the standard deviation will not change.

There will still be the same number of students with the same deviation from the new mean, because their score have moved too.