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 the number of children of the class be x

Then, number of notebooks each child will get = x/8

If the number of children were x/2

Number of notebooks each child will get = 16

Now, According to the question

Total number of notebook is constant

So, (x/2) × 16 = x × (x/8)

⇒ x = 64

So, total number of notebooks = 64 × 8

⇒ 512

**∴ Total number of notebooks were distributed is 512.**