Question

A professor informs her class that a test is very difficult, but the grades will be curved. Scores for the test are normally distributed with a mean of 25 and a standards deviation of 5. If she curves the grades by adding 50 to each grade, What is the new mean? What is the new standard deviation?

Answer 1

The new mean will be 25+ 50 = ?

The standard deviation will remain the same.

Answer 2

The new mean is 75 (25 + 50); however the standard deviation stays at 5 because she adds the same amount of points to all grades, so the curve is just shifting up rather than changing shapes.