In an institute, 60% of students are boys and rest are girls. Furr 15% of boys and 7.5% of girls are getting a fee waiver. If number of those getting a fee waiver is 90, find total number of students getting 50% concessions if it is given that 50% of those not getting a fee waiver are eligible to get half fee concession?

Let us assume there are 100 students in the institute.
Then, number of boys = 60
And, number of girls = 40
Further, 15% of boys get fee waiver = 9 boys
7.5% of girls get fee waiver = 3 girls
Total = 12 students who gets fee waiver
But, here given 90 students are getting fee waiver. So we compare
12 = 90
So, 1 = $$\frac{{90}}{{12}}$$ = 7.5
Now number of students who are not getting fee waiver = 51 boys and 37 girls
50% concession = 25.5 boys and 18.5 girls (i.e. total 44)
Hence, required students = 44 × 7.5 = 330