Two cubes have volumes in the ratio 1:27.the ratio of their surface areas is
(a)1:3
(b)1:8
(c)1:9
(d)1:18
For a cube of 1 unit length, it's volume is 1. For a cube of side length 3 units, its volume is .
So their side lengths are in the ratio 1:3.
The surface area of a cube is given by .
So the surface areas will be 6 and 54. Since 54 is 9 times 6, the ratio of their surface areas will be 1:9.