SOLUTION: if i have an average of 84% and my final exam is worth 20% of my final mark, what mark would i need on my exam to get a 90% average

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Question 941409: if i have an average of 84% and my final exam is worth 20% of my final mark, what mark would i need on my exam to get a 90% average
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
if i have an average of 84% and my final exam is worth 20% of my final mark, what mark would i need on my exam to get a 90% average.
:
Let x = your exam grade
The ratio of previous grade to exam 8:2, so we can write an equation like this
%28%282x+%2B+8%2884%29%29%29%2F10 = 90
multiply both sides by 10
2x + 672 = 900
2x = 900 - 672
2x = 228
x = 228/2
x = 114, greater than 100 so it looks like it is impossible to get a 90
:
:
If you get 100 in your exam: (200+672)/10 = 87.2 is your average