DRDO Multi tasking staff Model paper 1

Let the 3 numbers be, 6x, 3x, 2x, respectively.
Average = (6x + 3x + 2x)/3 = 638
⇒ 11x = 638 × 3
⇒ x = 174
∴ Difference between 1st and 3rd numbers = 6x - 2x = 4x = 4 × 174 = 696
Alternate method∶
Let the three numbers be A,B and C
A = 2B
A = 3C
Average = (A + B + C)/3 = 11A/18
⇒ 638 = 11A/18
⇒ A = 1044
C = 1044/3 = 348
∴ Difference between the first and third number = 1044 – 348 = 696