The average weight of the boys in a class is 69.3 kg and that of the girls in the same class is 59.4 kg. If the average weight of all the boys and girls in the class is 63.8 kg, then the percentage of the number of boys in the class is:

$44\frac{4}{9}$

Let's assume of no. boys in class are x and girls are y.

As, Sum = number x Avg. and as per given condition in question

69.3x + 59.4y = 63.8 (x + y)

9.9x + 59.4 (x + y) = 63.8 (x + y)

9.9x = 4.4 ( x+ y)

\(\frac{x}{x + y}\) = \(\frac{4.4}{9.9}\)

% of boys = \(\frac{x}{x + y}\)  x 100

                = 44.444 = 44\(\frac{4}{9}\)