The surface areas of similar solids is proportional to the square of their sides since the ratio of sides is 1 : 3 their surface areas have the ratio 1²: 3² or 1:9 so the surface area is 9(10.4) or 93.6
or
original width = x original length = y original heigt = z original surface area = 2(xy) + 2(xz) + 2(yz) = 2(xy + xz + yz)
new width = 3x new length = 3y new height = 3z new surface area = 2(9xy) + 2(9xz) + 2(9yz) = 18(xy + xz + yz)
ratio of new to old = 18(xy + xz + yz) : 2(xy + xz + yz) = 9:1
