SOLUTION: A teacher bases her class grade on four exams @100 pts. each. George has taken 3 exams with an average grade of 87%. What does he need on his fourth exam, to give him a final gr

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Question 52263: A teacher bases her class grade on four exams @100 pts. each. George has taken 3 exams with an average grade of 87%. What does he need on his fourth exam, to give him a final grade of 90%?
I have no idea. Please help!!
Found 2 solutions by atif.muhammad, tutorcecilia:
Answer by atif.muhammad(135)   (Show Source): You can put this solution on YOUR website!
If he needs a final average of 90%, then over 4 exams, he must have accumulated 360 out of the possible 400 marks.

He has already done 3 exams with an average of 87%, which is 261 marks (87 x 3).

He wants 360, he has 261. Hence, he needs 99 marks in his last exam to get the 90% average.

Answer by tutorcecilia(2152)   (Show Source): You can put this solution on YOUR website!
Since the average of the three exams is 87%, let it count as one exam:
(87+x)/2=90 [Solve for x]
87+x=180
x=93% is needed.

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