Question

A student's test grades are 75, 79, 88, and 94. What score of the fifth exam will make the average at least 85?

Write your answer as an inequality statement. Use x as the variable.

Answer 1

89≤x

Explanation:

This involves the combination of the average formula as well as use of an inequality. The first step is to write an inequality to represent the situation.

85≤(75+79+88+94+x)/5

85*5≤(75+79+88+94+x)/5*5

425≤75+79+88+94+x

425≤336+x

425-336≤336+x-336

89≤x

The student will need to make at least an 89 on the fifth exam to make an average of at least 85.