Two natural numbers are in the ratio 3 : 5 and their product is 2160. The smaller of the numbers is -

Answer: Option D

Let the numbers be 3x and 5x
Then,
= 3x × 5x = 2160
⇒ 15x² = 2160
⇒ x² = 144
⇒ x = 12
∴ Smaller number = 3x = 3 × 12 = 36