SOLUTION: Suppose Amanda's quiz average is 86, and these are her grades: 84,88,82,90,92,x, where x is unknown. Can you determine the missing grade? If yes, calculate. If not, why not?

Question 47400: Suppose Amanda's quiz average is 86, and these are her grades: 84,88,82,90,92,x, where x is unknown. Can you determine the missing grade? If yes, calculate. If not, why not?
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
To find the average of a set of numbers (grades), add the numbers and divide by the number of numbers (6 in this case). Amanda's average is 86, so:
simplify and solve for x.
Multiply both sides of the equation by 6.
Subtract 436 from both sides.

The missing grade is 80.

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