Tamera has test scores of 88,78,98,88, and 78. She was told that her final test grade average is the highest C possible as a whole number. What was her last test score?

I am assuming that the highest C grade is 82.

There are 5 known test scores and 1 unknown for a total of 6 tests.

82 * 6 = 492

88 + 78 + 98 + 88 + 78 = 430

492 - 430 = 62

Tamera's last test score is 62. It resulted to an average test grade of 82.