The average weight of a group of boys is 48 kg. If 8 boys of average weight 51 kg leave and 3 boys of average weight 42 kg join the group, then the average weight of group decreases by 1 kg 50 gm. Find the initial number of boys in a group
Let there are 'n' boys in a group initially, then their total weight=48n
When, 8 boys of average weight 51 kg leave and 3 boys of average weight 42 kg join the group, then of boys left = n-8+3 = n-5
New average of a group = (48n - 8*51 + 3*42) / (n-5) = (48 - 1.05)
48n - 408 + 126 = 46.95n - 234.75
1.05n = 47.25
n = 45
Correct Option 5)