Originally, the ratio of above 90 points to below 90 points was1/5: (1-1/5) =1:4 = 2: 8.

Later, the ratio of more than 90 points to less than 90 points was 3/7: 1 = 3: 7.

The total number of students in this class is 5 ÷ (3-2) × (3+7) = 50 (people).