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**