Correct Answer - Option 3 : 24

**Given:**

Two numbers are 48 and 12.

**Concept Used:**

When a, b, c and d are called in proportion, where a and d are called extremes and b and c are called means.

Product of extremes = Product of means

i.e. ad = bc

and Mean Proportional of a and b is √(a × b)

**Calculation:**

Let the mean proportion of 48 and 12 be x.

Here, a = 48 and b = 12

So, a ∶ x = x ∶ b

⇒ a/x = x/b

⇒ a × b = x^{2}

⇒ x = √(a × b)

⇒ x = √(48 × 12)

⇒ x = √(576)

⇒ x = 24

**∴ The mean proportional of 48 and 12 is 24.**