The ratio of the area of two square, one having and double its diagonal than the other is?

Let the diagonal of one square be (2d) cm
Then, diagonal of another square = d cm
∴ Area of first square = [ 1/2 x (2d)²] cm²
Area of second square = (1/2 x d²) cm²
∴ Ratio of area = (2d)²/ d²
= 4/1 = 4: 1