A graduate statistics class is unhappy with their midterm grades. The professor will curve the grades only if the class figures out how much the curve needs to be in order for the mean score to equal 80.

What should the curve for the class be if these are the midterm scores for the members: 72, 80, 75, 74, 73, 79, and 72.

a. 10

b. 5

c. 6

d. 2