Math avg problem

[Electrons]

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How do you setup the one below?

The student's current midterm scores are 81, 85, 95. The final exam is worth 1/3 of total grade. What does the student need to get on the final to get an average of 90?

 

[doc3232]

How do you setup the one below?

The student's current midterm scores are 81, 85, 95. The final exam is worth 1/3 of total grade. What does the student need to get on the final to get an average of 90?

Average of midterms is 87.
Then lets solve...I do this a lot to find out what I need to get on the final for my classes.
0.666667 x 87 + 0.3333333 x (the final grade) = 90
Solve for the final grade.
Hope this helps

 

[Electrons]

Hey thanks.

 

[murff05]

Why do you use the .6666 x the average?

 

[Thundercatz]

Why do you use the .6666 x the average?

Since the final is 1/3 of his average, his test averages account for 2/3 or .66 of his average.

(2/3)(87) + (1/3)(x) = 90

Hope that helps!

 

[Electrons]

Why do you use the .6666 x the average?

It's really like this, find the avg of the 3, then

2/3(87) + 1/3(x) = 90

solve for x