Solve. Use interval notation to express the range.
-On the first four exams, your grades are 79, 82, 75, and 80. There is still a final exam, and it counts as two grades. You are hoping to earn a C in the course. This will occur if the average of your six exam grades is greater than or equal to 70 and less than 80. What range of grades on the final exam will result in earning a C?
A) [52, 82)
B) [52, 82]
C) [34, 84]
D) [34, 84)

Question

Quizplus · Accepted Answer

To find the range of grades on the final exam that results in a C, calculate the average of all six grades. Let x be the grade on the final exam. The average is (79 + 82 + 75 + 80 + x + x) / 6. Set up the inequality 70 ≤ (316 + 2x) / 6 < 80. Solving gives 52 ≤ x < 82. Thus, the range is [52, 82).

Solve. Use Interval Notation to Express the Range