SOLUTION: an arithemetic student needs an average of 70 or more to receive credit for the course. She scored 72, 66, 68 on the first three exams. Write an inequality representing the score s

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Question 82417: an arithemetic student needs an average of 70 or more to receive credit for the course. She scored 72, 66, 68 on the first three exams. Write an inequality representing the score she must get on the last test to receive credit for the course.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
an arithmetic student needs an average of 70 or more to receive credit for the course. She scored 72, 66, 68 on the first three exams. Write an inequality representing the score she must get on the last test to receive credit for the course.
:
Using the standard "average" equation; let 4th (unknown) score = x:
%2872+%2B+66+%2B+68+%2B+x%29%2F4=> 70
:
Multiplying equation by 4 gets rid of the denominator:
72 + 66 + 68 + x => 4(70)
:
206 + x => 280
:
x => 280 - 206
:
x => 74, the score required to at least get a 70 average:
:
Check:
72+%2B+66+%2B+68+%2B+74%29%2F4 =
280%2F4 = 70