If i have a 82.31% grade average in a math class. If the final exam is 31% of my grade. What do i need to get on the final exam to receive a 75% in my math clas

Question

need help answering a algebra question

Answer 1

This question is about finding the weighted average of a set of numbers. Say, for instance, that at your school homework is 25% of your grade, tests are 50% of your grade, and classwork is 25% of your grade. Then to find your overall grade, you would need to multiply your grade in each category by how much that category counts towards your grade:

 

 (homework average x .25) + (test average x .5) + (classwork average x .25) = overall grade

 

For your specific problem, there are only 2 categories - the class average and the final exam. If the final exam is worth 31%, then the class average must be worth 100-31 = 69%. So then we set up the problem using the format above:

 

(class average x .69) + (final exam grade x .31) = overall grade

 

(82.31 x .69) + (final exam grade x .31) = 75

 

56.7939 + (final exam grade x .31) = 75

-56.7939                                            -56.7939

 

final exam grade x .31 = 18.2061

divide by .31                     divide by .31

 

final exam grade = 58.73

 

I hope this helps!

 

-Bailey S.

 

 

Answer 2

Hi Spences;

Welcome to Wyzant Answers!!!

82.31%=0.8231

75%=0.75

31%=0.31

(0.8231)(0.69)+(x)(0.31)=0.75

(0.5679)+(x)(0.31)=0.75

Let's subtract 0.5679 from both sides...

(x)(0.31)=0.1821

Let's divide both sides by 0.31...

x=0.5874

58.74%

Answer 3

Spencer, hopefully you'll get higher than a 75% class grade, going in with an 82.31%! However --

1) set up an equation expressing your final grade calculation. What goes into calculating it? I suspect you know -- all the work of the year. 

2) You know the grade for one part of the work (class so far), and need to find the grade for "the other part" (your final) Let's call it "x". You also know what you are "aiming at" as a class grade -- 75%.

3) So, how do you calculate an average? = contributions from all the respective work

4) If the final counts for 31%, how much does all the rest count for? = 1-0.31=0.69  (100% - 31% = 69%).

5) SO, your calculation should be: 0.8231 * 0.69  +   x * 0.31  =  0.75 (expressing all grades as decimals rather than in %'s. You don't NEED to do this; you could carry through units of %, just as long as you're consistent about treating all the data the same throughout the calculation!) The reason here: add up all the bits of your various grades which give you credit = a *weighted* average.

6) Solve to get x = 0.5873   -- that is, you need to pull a 59% on your final exam (answer has been rounded to two significant figures, which is the least precision of any of your input data).

7) Don't forget to always check for step (6): rounding of results AFTER doing ALL the calculations! ANd don't forget to always carry ALL units through your calculations -- units are your friends; you take care of your friends and they'll take care of you (if your units don't work out, you did the problem wrong!).