Gear ratios

One of my team mates thinks a 1:3.125 gear ratio for the arm is impossible, we use a 1:5 right now for our arm. Many people on the forum say that they have that gear ratio, so can someone explain how they do it?[what gear arrangement]

A 1:3.125 gear ratio is possible, it is a 1:5 ratio with high speed motors. Our team used that ratio with 8 motors on our dumper