Sonya received grades of 85, 90, 92, 84 on four math tests. What is the lowest grade that Sonya can score on the fifth test for her average to be greater than 90?
(85 + 90 + 92 + 84 + x)/5 > 90
85 + 90 + 92 + 84 + x > 450
x > 99
Or, so far the 90 and the 92 put her 2 above 90, but the 85 and the 84 put her
11 below the 90, so she needs 11-2 or 9 above 90 to get the 90 average,
thus 99.
Good luck!!