Date: 11/16/95 at 18:32:41 From: Fortino Martinez Subject: Averaging grades If Johnny has a 82% average for the 1st 9wks and a 75% average for the 2nd 9wks, what grade would he have to get on the final to recieve 80% semester grade in this class. The grades are weighted as follows: each 9wks 40 % and the semester test 20%. K Riggins CCHS
Date: 11/19/95 at 15:4:26 From: Doctor Ethan Subject: Re: Averaging grades Okay, good question. Here is how it works. .4 +.4 + .2 = 1 So what we are going to do is to set up an equation involving the percentages of the present grades and how they add up. It looks like this: .4(82) + .4(75) + .2 (XX) = 80 So to solve for XX we simplify to 32.8 + 30 + .2(XX) = 80 SO..... .2(XX) = 80 - 32.8 - 30 So .2(XX) = 17.2 Now divide both sides by .2 and XX = 86. Hope that helps. -Doctor Ethan, The Geometry Forum
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.