Ina class of 40 students, 45% are girls and the remaining are boys.If the average of the girls’ marks is 54 and that of the boys is 46, what is the average of the whole class?
Number of girls = 45% of 40 = 18 and boys = 40-18=22
Average of whole class = $$\frac{\left(18\times\ 54+22\times\ 46\right)}{40}=49.6$$
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