You scored 88,92, and 87 on three tests. Write and solve an equation to find the score you need on the fourth test so that your mean test score is 90.

Question

You scored 88,92, and 87 on three tests. Write and solve an equation to find the score you need on the fourth test so that your mean test score is 90.

Answer 1

88, 92, 87 are 2 below 90, 2 above 90 and 3 below 90

-2+2-3 =-3

that sums to 3 below 90

88 and 92 already average to 90

to balance the 87 which is 3 below 90, you need a grade that's 3 above 90, that's 93