Question

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.

Answer 1

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.