If Susan takes two tests and makes a makes a 54/100 on the first test and a 63/100 on the second test, and is given a third test and makes an 80/100(which can only count as 20% of her total grade for all three test, what is her final grade/score.
Since the 54% and the 63% grades count as 80% of her grade (and assuming therefore that each counts as 40%), the final grade is
(54+63)(0.4) + 80(.2) = 62.8
To calculate Susan's final grade, we need to consider the weightage given to each test. Given that the third test only counts for 20% of her total grade, the first and second tests must count for the remaining 80%.
Let's calculate the weighted scores for each test:
First test: 54/100 * 80% = 0.54 * 0.8 = 0.432
Second test: 63/100 * 80% = 0.63 * 0.8 = 0.504
The third test score is already weighted correctly as 80/100 * 20% = 0.8 * 0.2 = 0.16
Now, let's calculate Susan's final grade by summing up the weighted scores:
Final grade = Weighted score of first test + Weighted score of second test + Weighted score of third test
= 0.432 + 0.504 + 0.16
= 1.096
Therefore, Susan's final grade is 1.096, which can also be represented as 109.6/100 or 109.6%.