SOLUTION: A math student has a 100 homework average and test grades of 99, 100, and 97. The homework average counts 15%, each test counts 20%, and the final exam counts 25%. What is the lo

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Question 1062809: A math student has a 100 homework average and test grades of 99, 100, and 97. The homework average counts 15%, each test counts 20%, and the final exam counts 25%. What is the lowest grade the student can get on the final exam and still get an A (an average of 90 or better) in the class?
Found 2 solutions by math_helper, Theo:
Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!

The variable is the score on the final, let's call it x.
+%280.15%29%28100%29+%2B+%280.20%29%2899%2B100%2B97%29+%2B+%280.25%29x++%3E=+90+
++15+%2B+59.2+%2B+0.25x+%3E=+90+
+++74.2+%2B+0.25x+%3E=+90+
++++0.25x+%3E=+15.8+
+++highlight%28+++++++x+%3E=+63.2+%29

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
homework = 100
test grades of 99, 100, 97

homework average counts 15%
each test counts 20%
final counts 25%

.15 * 100 = 15
.20 * 99 = 19.8
.20 * 100 = 20
.20 * 97 = 19.4
.25 * x = .25 *x

15 + 19.8 + 20 + 19.4 + .25 * x >= 90

combine like terms to get 74.2 + .25 * x >= 90

subtract 74.2 from both sides of the equation to get .25 * x >= 90 - 74.2

simplify to get .25 * x >= 15.8

divide both sides of this equation by .25 to get x >= 63.2

he needs to get greater than or equal to 63.2 on the final to get a final average greater than or equal to 90.