The LCM and ratio of four numbers are 630 and 2 : 3 : 5 : 7 respectively. The difference between the greatest and least numbers is = ?

Answer: Option C

Let the numbers be 2x, 3x, 5x and 7x respectively
Then their LCM = (2 × 3 × 5 × 7)x = 210x.[∴ 2, 3, 5, 7 are prime numbers]
So, 210x = 630 or x = 3
∴ The numbers are 6, 9, 15 and 21
Required difference = 21 - 6 = 15