What is the IMA of a screwdriver with a shaft radius of 4 mm and a handle radius of 12 mm.?

The ideal mechanical advantage (IMA) of a screwdriver is calculated by dividing the shaft radius by the handle radius. In this case, the IMA would be 4 mm (shaft radius) divided by 12 mm (handle radius), resulting in an IMA of 1/3 or approximately 0.33.