Let one side of a cube = x cm.
∴ Its volume = x3 cu.cm.
If the length is reduced by 50% then the new length of the cube =\frac{x}{2} cm.
∴ Volume of the new cube =(\frac{x}{2} cm)^3=\frac{x^3}{8}
∴ The ratio of the volume of the original cube & volume of the new cube
=x^3: \frac{x^3}{8}=1: \frac{1}{8}= 8 : 1