SOLUTION: A student received scores of 72, 85, 53 and 80 on the first four quizzes. What minimum score does the student need on the fifth quiz to average 70 for all 5 quizzes?

Question 896556: A student received scores of 72, 85, 53 and 80 on the first four quizzes. What minimum score does the student need on the fifth quiz to average 70 for all 5 quizzes?
Found 2 solutions by vja_1994, richwmiller:
Answer by vja_1994(6) (Show Source): You can put this solution on YOUR website!
First add all the received scores:

Let x be the score of the fifth quiz.
We know the student wants an average of 70 for all 5 quizzes, yet he has only taken 4 quizzes.
(Average of 5 quizzes)=(total score of all 5 quizzes)/(# of quizzes)
When you plug in the values you know it will look like this:

Solve for x:
Multiply each side of the equation by 5.

Subtract 290 from each side of the equation.

The student will need a 60 on his fifth quiz to achieve an average of 70 for all 5 quizzes.
-Alejandro
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
another way
72-70=2
85-70=15
53-70=-17
80-70=10
for a difference of +10
x-70=-10
x=60
72-70=2
85-70=15
53-70=-17
80-70=10
60-70=-10
for a difference of 0
72+ 85+ 53 + 80+60=350
350/5=70

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