Centre of mass of a disc with a circular hole cut out

This type of question, asked 2 times: 2021 Paper 2, 23 Jan 2025. All 2 questions below, oldest first.

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Question 1
2021 Paper 2
5 $\left( \frac{a}{2} \right)$
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Question 2
23 Jan 2025
20 $Consider a circular disc of radius 20 cm with centre located at the origin. A circular hole of a radius 5 cm is cut from this disc in such a way that the edge of the hole touches the edge of the disc. The distance of centre of mass of residual or remaining disc from the origin will be-$
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