Explanation:
the scale factor of similar objects apply to every line and side length.
we see here the ratio of small side length to large side length is 3/9 = 1/3.
so the small side length is 1/3 if the large side length.
a surface is airways the multiplication of 2 dimensions. so, the scale factor is to be used twice in this multiplication and therefore squares.
so, small surface to large surface is 1/3 × 1/3 = 1/9.
and a volume is airways the result of a multiplication of 3 dimensions. so, the scale factor is then 3 times in that multiplication and is therefore cubed.
so, small volume to large volume is 1/3 × 1/3 × 1/3 = 1/27