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प्रश्न
There are 45 students in a class, in which 15 are girls. The average weight of 15 girls is 45 kg and 30 boys is 52 kg. Find the mean weight in kg of the entire class.
उत्तर
Here n1 = 15, n2 = 30, X1 = 45 Kg and X2 = 52 Kg.
∴ `bar"X"` = `("n"_1bar"X"_1 + "n"_2bar"X"_2)/("n"_1 + "n"_2) = (15 xx 45 + 30 xx 52)/(15 + 30)"Kg"`.
= `(2235)/(45)"kg"`
= 49·67kg.
Hence, the mean weight of the entire class is 49·67kg.
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