Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Grade Averages


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

    
Associated Topics:
Middle School Algebra

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/