The average, or mean, D, of three exam grades, x, r, and v, is given by the
following formula.
X+r+V
D
3
(a) Solve the formula for v.
(b) Use the formula in part (a) to solve this problem. On your first two exams, your
grades are 85% and 86%: x=85 and r= 86. What must you get on the third exam
to have an average of 90%?
(a) The formula is v= 3D-x-r.
(b) The answer is.
