The side of the innermost square is 2 + 2 = 4 and the side of the outermost square is 2 × (2 + 2 + 2) = 12.
Perimeter of the innermost square = 4 × 4 = 16
Perimeter of the outermost square = 4 × 12 = 48
Ratio of perimeter of the outermost square to the perimeter of the innermost square = 48⁄16 = 3