CASE 1
lets take, total number of boys = 10 = number of girls
total weight of boys = 150 x 10 = 1500
lets say 9 boys weight 140 = 9 x 140 = 1260, so last boy weights 1500-1260 = 240
Here no. of boys weighting over 150 = 1
similarly, total weight of girls = 110 x 10 = 1100
lets say 9 girls weight 111 = 111 x 9 = 999, so last girl weighs 1100-999 = 101.
here, no. of girls weighting over 110 = 9
IN this case no. of girls are more
CASE 2
total weight of boys = 150 x 10 = 1500
lets say 9 boys weight 155 = 9 x 155 = 1395, so last boy weights 1500-1395 = 105
Here no. of boys weighting over 150 = 9
similarly, total weight of girls = 110 x 10 = 1100
lets say 9 girls weight 100 = 100 x 9 = 900, so last girl weighs 1100-900 = 200
here, no. of girls weighting over 110 = 1