Find a third proportional to the numbers 2 and 4.

6 7.5 8 9

8

⇒ a : b :: b : c Third proportion (c) = \(\frac{b^2}{a}\) Here, a = 2, b = 4, ∴ c = \(\frac{b^2}{a}\) = \(\frac{16}{2}\) = 8