To earn an A in a course, a student must have a final grade of at least 0.9. On the first our examinations, a student scores 0.87, 0.89, 0.91, and 0.85. If the scores in the final examination counts as two examinations, what must this student get on the finals to earn an A (0.9) in the course?
Mean = ∑x/n
(.87 + .89 + .91 + .85 + 2x)/6 = .9
Solve for x.