The average weight of 25 boys in a class is 58.75 kg and that of the remaining 15 boys is 49.25 kg. The average weight of all boys in the class is?

55.19 kg

No. = 25 & 15 = 5 : 3

Avg. = 58.75 &  49.25

diff. of avg. = 9.50

Sum of ratio of no. = 5R +3R = 8R = diff. of avg.

8R = 9.50

1R = \(\frac{9.50}{8}\)

3R = 3 × \(\frac{9.50}{8}\) = \(\frac{28.50}{8}\) = 3.56

Avg. of all = 58.75 - 3.56 = 55.19