Three small spherical masses are located in a plane at the positions shown below.
The masses are Q=0.700 kg, R=0.400 kg, and S=0.800 kg. Calculate the moment of inertia (of the 3 masses) with respect to an axis perpendicular to the xy plane and passing through x=0 and y=-3. [Since the masses are of small size, you can neglect the contribution due to moments of inertia about their centers of mass.]
The Attempt at a Solution
I tried finding the Center of mass with turned out to be (-0.42, -1.15) and then tried to find the radius to plug into the equation, but that gave me the wrong answer and I am not sure where to even start with this problem.