The average weight of a class of 50 students is 48.6 kg. If the average weight of the 20 boys is 54 kg, then find the average weight (in kg) of the girls in the class.
Total weight of 50 students =Â $$50\times48.6=2430\ .$$
Total weight of boys =Â $$20\times54=1080\ .$$
Total of 30 girls =Â $$2430-1080=1350\ .$$
So, Average weight of them = $$\frac{1350}{30}=45\ .$$
C is correct choice.
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