The average weight of boys in a class is 30 kg and the average weight of girls in the same class is 20kg. If the average weight of the whole class is 23.25 kg, what could be the possible strength of boys and girls respectively in the same class?

Given:

• Average weight of boys = 30 kg
• Average weight of girls = 20 kg
• Average weight of entire class = 23.25 kg

Let number of boys = x, number of girls = y

Use the weighted average formula:

(30x + 20y) / (x + y) = 23.25

Multiply both sides by (x + y):

30x + 20y = 23.25(x + y)

Eliminate decimals:

=> 30x + 20y = (93/4)(x + y)
=> Multiply both sides by 4:
120x + 80y = 93(x + y)

Now expand the right-hand side:

120x + 80y = 93x + 93y
=> 120x - 93x = 93y - 80y
=> 27x = 13y
=> x/y = 13/27

Therefore, possible strength of boys and girls =

13 boys and 27 girls (or any multiple of this ratio).