The grading scale for a C in Amy's biology class is an average on tests between 70% and 80%, inclusive. Amy has 64%, 84%, and 78% on the first three tests this semester. What range of scores on
The fourth test would give her a C?
A)Between 59% and 89%, inclusive
B)89% or better
C)Between 54% and 94%, inclusive
D)Between 70% and 80%, inclusive

Question

Quizplus · Accepted Answer

To find the range of scores for the fourth test that would give Amy a C, calculate the average of the four test scores and set it between 70% and 80%. Solving the inequality 70 ≤ (64 + 84 + 78 + x)/4 ≤ 80 gives the range 54 ≤ x ≤ 94.

The Grading Scale for a C in Amy's Biology Class