Malena has taken four tests so far. Her scores are 92%,80%,88%,93%. What score does she need to get on the fifth test to raise her average grade to 90%?
To calculate the average you add up all the scores and divide by the number of scores (5) add all the current test scores and allow X to be the unknown score: 92+80+88+93+X: or 353 + X
set up equation:
(353+X) ______ = 90 5
Multiply both side of the equation by 5 to clear the fraction resulting in:
353+X=450
Subtract 353 from both sides of the equation:
x = 97
So the test score needed to get a 90 average is 97.
