Correct Answer - Option 3 : 512
Given
If number of child half then number of notebooks have each child = 16
Formula used
If a : b :: c : d
then a × d = b × c
Calculation
let number of children of a class = x
Then, number of notebooks each child will get = x/8
If the number of children = x/2
Number of notebooks each child will get =16
⇒ x : x/8 :: x/2 : 16
⇒ x = 64
So, Total Number of notebooks books = 64 × 8 = 512
∴ The total number of notebook is 512