To solve this problem you must apply the proccedure shown below:
1. You must apply the following formula for calculate the IMA of the doorknob shown in the figure attached of the problem above:
IMA=outer radius/inner radius
outer radius=3 cm
inner radius=0.5 cm
2. When you substitute these values into the formula, you obtain:
IMA=3 cm/0.5 cm
IMA=6
Therefore, the answer is: 6
