In a class of 40 students, 60% are girls. The average of the girls’ marks is 72 and that of the boys is 54. What are the average marks of the whole class?
ratio of girls and boys = 60% : 40% = 3 : 2
Let the total number of girls and boys in the school is $$3x$$ and $$2x$$ respectively.
Total marks of the girls = avg marks $$\times$$ total girls= $$72\times3x$$
Total marks of the Boys = $$54\times2x$$
Avg marks of the school = $$\frac{72\times3x+54\times2x}{3x+2x}$$ = 64.8
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