Question 142080
a. 63-51=12  (1 standard deviation below the mean). This is asking for 50%+34%=84% of the tests. .84*800=672. In words, it was asking for the amount of tests scoring higher than 1 standard deviation below the mean.

b. z=(39-63)/12=-2. The score lies precisely 2 standard deviations below the mean.

c. z=(82-63)/12=1.58333...