Question

In a class of 39 students there are 26 girls. The average weight of this girls is 42 Kg and the average weight of the full class is 48 Kg.
What is the average weight of the boys of the class?

Ayuda por favor
Gracias

Answer 1

We can simplify the whole class room in two groups: boys and girls, besides we have there's 26 girls and 13 boys
.
The average weight of the whole class is 48 kg.
The average weight of the girls is 42 kg.

We can build the equiation as:
(42+X)/2 = 48

Then we clear the X and do the operations:
42 + X = 48*2

X = 96 - 42

X = 54 

We can asumme the average weight of the boys is 54 kg.