Question

To receive a C grade, a student must average more than 77 but less than or equal to 85. If Isabella

received a C in the course and had five grades of 78, 79, 74, 64, and 85 before taking the final exam,
what were the possible grades for her final if there were 100 points possible? (Assume all six grades are weighted equally and let x represent the unknown score.

Answer 1

She must have scored greater than 82 and up to 100 on the final

Explanation:

Her average had to be between 77 or <= 85

for > 77:

(78+ 79 + 74 + 64 + 85 + x)/6 > 77

x > 82

for <= 85: (78+ 79 + 74 + 64 + 85 + x) / 6 <=85

x<=130 ( but she can only score up to 100)