From statement I, Number of boys = 9x Number of girls = 7x From statements I and H, Average weight of boys= y kg. Average weight of girls = (y - 4) kg. ∴ y x 9x + (y — 4) x 7x = (9x + lx) x 44.25 ∴ 9y + 7y - 28 = 16 x 44.25 = 708 => 16y = 708 + 28 = 736 ⇒ y =