Carcass wrote:
The average of John’s test scores in his economics class is 80%. Only one test remains, and it is weighted at 25% of the final grade. If his final grade is based entirely on his test scores, what is the lowest percent John can receive on the final to earn an 85% in the class?
A. 96%
B. 97%
C. 98%
D. 99%
E. 100%
Kudos for the right answer and explanation
let the total no of tests before the final test = x
the final test = 25% of the final grading
therefore, tests before the final test = 75% of the final grading
therefore,
x = 75% final grading
1 = 25% final grading
hence, x =3
let the total no of scores for the first 3 test = P
P/3 = 80
P=240
let the final test score = Y
Avg of all test = (240 + Y)/4 = 85
Y =100
hence, ans is E