I agree with the other answer. Here's another way to see why the answer is 1:27
The surface areas are in ratio 1:9. This means we could have one square that has area 1 and the larger square is area 9.
The smaller square has sides of 1 and the larger square has sides of 3 (square root both area values).
Now if we had a cube that has dimensions of 1 unit, then the volume is 1*1*1 = 1 cubic unit. If we had a larger cube with dimensions of 3 units, then the volume is 3^3 = 3*3*3 = 27 cubic units. We can fit 27 smaller 1x1x1 cubes into the larger 3x3x3 cube.
