Question 332570
A student has earned scores of 87, 81, and 88 on the first 3 of 4 tests. If the student wants an average (arithmetic mean) of exactly 87, what score must she earn on the fourth test?
.
Let x = score of fourth test
then
(87+81+88+x)/4 = 87
.
Multiplying both sides by 4:
(87+81+88+x) = 348
256+x = 348
x = 348-256
x = 92