Answer:
The overall final score of the student is 75.4, in letter scale, a C.
Explanation:
Assuming that numbers are repeated (1010% means 10% and so on).
To find his overall final score, we have to take into account that it is a weighted average.
A weighted average is one where each score (x) has a specific weighing, for example, midterm's weighing in this case is 10%. If we add all weighings, we should get 100% (it is the case). The formula is:
![\mbox{Weighted average}= \sum_(i=1)^(n)x_(i)*\mbox{weighing}_(i)](https://img.qammunity.org/2020/formulas/mathematics/college/y93pjulxxvobouuwawm5ugzt1twddl3i2i.png)
With our data:
![\mbox{Weighted average}=66*10\%+84*10\%+84*40\%+67*40\%=75.4](https://img.qammunity.org/2020/formulas/mathematics/college/zyzlxmg2rue31ozum0934bro3026kfe1p8.png)
As the mean is 75.4, higher than 70 but lower than 80, he earned a letter grade of C.