Algebraic word problem. What score is needed?

Question

Michael scores a 95, 87, 85, 93, and a 94 on his first 5 math tests. If he wants a 90 average, what must he score on the final math test?

Answer 1

86

To solve for the final score:

Add the five past test scores and you get 454. Then set up an algebraic equation where you add 454 to x, which is the final test score, and divide by six, because you want the average for 6 tests now. You make this equation equal to 90 because that is the average Michael wants and solve for x:

(454+x)/6 = 90

454+x = 540

x=86

Answer 2

He wants an average of 90 for 6 tests, so the total must be 540 (90 x 6). The first 5 tests totaled 454, so the 6th test must be the difference: 540 for 6 tests - 454 for the 1st 5 tests = 86 for 6th test.

Sorry, I didn't use algebra.

Answer 3

95 and 85 have an average of 90

93 and 87 have an average of 90

94 and 86 have an average of 90

an 86 is needed to get an average of 90 for all 6 scores

or sum the 5 to get 454

(454+x)/6 = 90

454 +x = 6(90) =540

x = 540-454 = 86

actually most instructors would round up to the nearest integer, so

all you need is an average of 89.5 to get a 90 and an A

89.5 x 6 = 537

x = 537-454 = 83

an 83 is enough to get a 90 average and an A letter grade