SOLUTION: If i have a 67% in math what do i need to get on the eoct that is worth 20% of my grade to pass the class?

Algebra ->  Average -> SOLUTION: If i have a 67% in math what do i need to get on the eoct that is worth 20% of my grade to pass the class?      Log On


   

Question 883807: If i have a 67% in math what do i need to get on the eoct that is worth 20% of my grade to pass the class?
Answer by SmithWillSuffice(4) About Me  (Show Source):
You can put this solution on YOUR website!
This is a question about weighted averages. In this case the "weights" are the proportions of the fimnal grade which are approtioned to each separate exam paper.
Assuming they have no other exams to make up their grade, and assuming a "pass" means getting above 50% overall, then we can solve this puzzle using simple algebra and knowing how to compute averages. We will also assume if EOCT is worth 20% of the overall grade, then the Maths score must be worth 80%. So these will be the weights for the final computed average. Weights do not always have to sum to =1, but if they are probabilities or percentages then they do need to sum to unity (otherwise it would imply you were missing something).

Let x+ be the minimum grade in the EOCT exam they need. If we knew +x+ then their overall average grade would be,
Overall = +%28+0.8%2A67+%2B++0.2%2Ax%29%2F%280.8%2B0.2%29.+
Remember, for weighted averages we divide the weighted sum by the sum of the weights, not the number of items averaged.
Then we are simply being asked to solve for +x+,
+50+=+%280.8%2A67+%2B++0.2%2Ax+%29%2F%281%29+
thus +50+=+0.8%2A67+%2B++0.2%2A+x+
thus +50+=+%288%29%2F%2810%29+%2A+67+%2B++%282%29%2F%2810%29+%2A+x++
thus +50+=+536%2F10+%2B++%282%29%2F%2810%29+%2A+x++
thus +%282%29%2F%2810%29+%2A+x+=+50+-++%28536%29%2F%2810%29++
thus +%282%29%2F%2810%29+%2A+x+=+%28500+-+536%29%2F%2810%29++
thus ++2%2Ax+=+500+-+536++
thus +2%2Ax+=+-36+
thus +x+=+-%2836%29%2F%282%29+
thus +x+=+-18.+
That's the answer, believe it or not!

What does it mean? It means you can afford a negative score on the final exam. Since placing your name on the exam paper will win you a score of 0\% at least, this is all you need. You cannot fail provided you turn up to hand in the EOCT exam paper. :-)
Reflect: If you don't believe that st answer, just imagine you do only get 0% on the EOCT exam. Then what is your final grade?
Answer: It will be,
+%280.8+%2A+67+%2B+0+%2A+0.2+%29%2F%280.8%2B0.2%29+=+53.6+
which is a pass.