One side surface area of a cube = x*x = x^2

Total 6 sides = 6x^2

As for the rectangular, Height (H) and Width (W) are same as Cube, x. Only Length = 2x.

L x H = 2x * x = 2x^2 ----> 4 sides = 2x^2 * 4 = 8x^2

W * H = x * x = x^2 ------> 2 sides = x^2 * 2 = 2x^2

Total 6 sides = 8x^2 + 2x^2 = 10x^2

Ratio of cube area to rectangular area = 6x^2 / 10x^2 ----> 6/10 ----> 3/5 (E)

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Jimmy Low, Frankfurt, Germany

Blog: http://mytrainmaster.wordpress.com

GMAT Malaysia: http://gmatmalaysia.blogspot.com