Answer:
90%
Explanation:
Because we're looking for the minimum score which Michaela could earn to for the mean of her quiz grades to be an 85% or above, we can use an inequality and allow x to represent the final score needed:
85 ≤ (72 + 77 + 84 + 86 + 92 + 94 + x) / 7
595 ≤ 505 + x
90 ≤ x
Thus, 90% is the minimum score Michaela must earn on the last quiz for the mean quiz grade to be at least 85% or higher.