To determine the similarity ratio, we need to compare the sides of the cubes. Unluckily, we are given the volumes, so we will need to find the sides by calculation.
First cube:
512 m^3
Taking the cube root (or thinking about it), we can find that the side length must be 8 m.
Second cube:
3375 m^3
Similar idea, we can find that the side length must be 15 m.
The similarity ratio is 15/8 or approximately 1.875.
