In a class there are 35 boys and 46 girls. The mean marks of boys are 50. The mean mark of class is 40. Find the mean marks of girls.
Total marks of boys = 35*50 → 1750
Total marks of girls = 46*gave
Total marks of class = (35 + 46)*40 → 81*40 → 3240
So we must have: 1750 + 46*gave = 3240
46*gave = 3240 - 1750
gave = (3240 - 1750)/46 ≈ 32.4
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