Question

10. Setting an average as a goal. You want to earn a 90% in a class. On the first three tests you scored a 90%, an 89%, and a 95%. What percent would you need on the fourth test to earn a 90%? Write it as an equation, then solve

Answer 1

To achieve an overall class average of 90%, after scoring 90%, 89%, and 95% on the first three tests, you would need to score at least 86% on the fourth test.

Step-by-step explanation:

To determine what percentage you would need on the fourth test to earn an overall average of 90% in a class, you can set up an equation that represents the average of the four test scores. Let's denote the unknown fourth test score as 'x'. The equation will be the sum of all your test scores divided by the total number of tests:

(90 + 89 + 95 + x) / 4 = 90

Multiply both sides by 4 to isolate the sum of the scores on one side:

90 + 89 + 95 + x = 360

Add up the known scores and subtract them from 360 to find 'x':

274 + x = 360

x = 360 - 274

x = 86

Therefore, you would need to score at least 86% on your fourth test to have an overall average of 90% in the class.