SOLUTION: Suppose a student has earned the following grades on her first four quizzes: 83, 72, 89, 78. What must she score on her fifth quiz in order to have a mean of 80 on all of her quizz

Algebra ->  Average -> SOLUTION: Suppose a student has earned the following grades on her first four quizzes: 83, 72, 89, 78. What must she score on her fifth quiz in order to have a mean of 80 on all of her quizz      Log On


   



Question 628886: Suppose a student has earned the following grades on her first four quizzes: 83, 72, 89, 78. What must she score on her fifth quiz in order to have a mean of 80 on all of her quizzes?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose a student has earned the following grades on her first four quizzes:
83, 72, 89, 78.
What must she score on her fifth quiz in order to have a mean of 80 on all of her quizzes?
:
Let x = score on the 5th quiz to have an 80 average
:
%2883%2B72%2B89%2B78%2Bx%29%2F5 = 80
Multiply both sides by 5 and solve for x