Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, then difference of first and third numbers is

Answer: Option D

Let the second number be x
Then, first number = 2x, 3^rd number = 4x
∴ 2x + x + 4x = 56 × 3
⇒ 7x = 168
⇒ x = 24
∴ Required difference
= 4x - 2x
= 2x
= 2 × 24
= 48