Question

Anne scored 75, 81 ,77 , and 83 in her four tests. What score should she get in her fifth test to have an average of 80?

Answer 1

She should get 84 in her fifth test to have an average of 80

(75 + 81 + 77 + 83 + x)/5 = 80

(316 + x)/5 = 80

[(316 + x)/5] (5) = 80(5)

316 - 316 + x = 400

316 + x = 400 - 316

x = 84

Answer 2

Remark

You set this up as (75 + 81 + 77 + 83 + x)/5 = 80 Combine the left

(316 + x)/5 = 80 Multiply by 5

316 + x = 80 * 5

316 + x = 400 Subtract 316

316 - 316 + x = 400 - 316

x = 84 <<<< Answer