Moment of Inertia & Radius of Gyration
Given identical rings are arranged in a hexagonal plane pattern so as to touch each neighbouring ring as shown in figure. Each ring has mass M and radius R. The moment of inertia of the system of seven rings about an axis passing through the centre of central ring and normal to plane of all rings is

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Answer: (a)
- Central ring: .
- Each outer ring centre is away: .
- So the answer is (a).