Question

Final grades are often computed using weighted averages. For example, Fran's teacher uses the following: homework 10%, quizzes 20%, and tests 70%.

Fran has an average homework score of 92. Her quiz score average is 68, and her test score average is 81. What final grade can Fran expect?
A) 73.5
B) 75.5
C) 78
D) 79.5

Answer 1

what is 92% of 10 ?
What is 68% of 20 ?

Do you see a pattern here?

Answer 2

Nope that's why I asked for help. :(

Answer 3

Okay

Answer 4

\[10\%=\frac{10}{100}=0.1\] and so \(10\%\) of \(92\) is \(0.1\times 92\)

Answer 5

This concept can be confusing at first. I'd bet this is your first experience with "weighted averages." For any one student, test scores contribute 70% of his grade.

Thus, if a particular student earns an average of 81 on his tests, we multiply (weight) that score by 0.70 (the decimal equivalent of 70%). Thus, the contribution of the test scores towards the final grade, for this particular student, is 0.70 (81).
Do the same calculation for each the homework and quizzes score for this same student.

Answer 6

You'll get 3 terms. Add these 3 terms together to calculate the overall score earned by this particular student.

Answer 7

I'm really slow I still do not get it

Answer 8

Not much sense in repeating what I've already said. Please share what you do understand and try to identify what you don't.

Please note: Suppose that some student got 100% in all three categories (homework, quizzes and tests).

Here is what the grade calculation would look like:

0.10(100) for homework
0.20(100) for quizzes
0.70(100) for exams

Adding these together gives us (0.1+0.2+0.7)(100), or (1.0)(100), or 100. Not surprising!

Suppose the same student got an average of 90% instead of 100% on his exams.

The grade calculation would look like:

0.10(100) for homework This comes out to 10
0.20(100) for quizzes This comes out to 20
0.70( 90) for exams This comes out to 63

Add up 10 and 20 and 63, and you get 93. Makes sense, doesn't it?

Now go back to the original problem and follow these examples.

Please show your work if you want feedback on it.