SOLUTION: My grade depends on 4 equally weighted tests. If my average from the first three is 92, what must I make on the fourth test to receive an average of at least a 90?

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Question 964291: My grade depends on 4 equally weighted tests. If my average from the first three is 92, what must I make on the fourth test to receive an average of at least a 90?
Answer by hkwu(60) About Me  (Show Source):
You can put this solution on YOUR website!
Your first three tests have a combined weight of 75%. Thus your current mark, counting only your first three tests, would be 92 * 0.75 = 69. Now, since 90 - 69 = 21, you'll need the weighted average of your last exam to be equal or greater than that. Thus
0.25x%3E=21
x%3E=84
If you get a 84 or higher on your last exam, you'll end up with at least 90.
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