SOLUTION: Flora had an average of 83% on her first 7 exams. What would she have to get on her eighth exam to obtain an average of 90%?

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Question 510906: Flora had an average of 83% on her first 7 exams. What would she have to get on her eighth exam to obtain an average of 90%?
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Let's find the sum of her first seven scores, we'll call this y:
y%2F7+=+83 Multiply both sides by 7.
y+=+581 Now you want the average of eight test scores to be 90. Lets call the score of the eighth test x, so...
%28581%2Bx%29%2F8+=+90 Multiply both sides by 8.
581%2Bx+=+720 Subtract 581 from both sides.
x+=+139
Flora will need to score 139% on test eight. Not possible!