SOLUTION: My question is about percentages: test 1 = 25% have 76% test 2 = 25% have 77% test 3 = 30% I need a 75% avg from my tests in order for me to add on the other 20%. I can f

Question 168105: My question is about percentages:
test 1 = 25% have 76%
test 2 = 25% have 77%
test 3 = 30%
I need a 75% avg from my tests in order for me to add on the other 20%. I can figure out my avg from test 1 and 2 but what is the formula to predict the lowest grade I can get from 3rd test considering it is worth 30% and not 25%?
quizzes = 5% have 100%
essay = 5% = have 100%
project = 10% ?? not finished
Can't figure out how much I need to get a 90% in class.
Thanks,
jessiejames
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
test 1 = 25% have 76%
test 2 = 25% have 77%
test 3 = 30% have x%
.
.25(76) + .25(77) + .30(x) >= 75
19 + 19.25 + .30(x) >= 75
38.25 + .30(x) >= 75
.30(x) >= 36.75
x >= 36.75/.30
x >= 122.5
.
This says you need to score 122.5% on test 3.
Which is impossible unless you can score "extra credit".

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