Volume numerically equal to k times surface area: find the radius

This type of question, asked 2 times: 17 Sep 2025 S1, 21 Sep 2025 S2. All 2 questions below, oldest first.

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Question 1
17 Sep 2025 S1
61 $The volume of a hemisphere is numerically equal to four times its curved surface area. Find its radius.$
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Question 2
21 Sep 2025 S2
55 $If the numerical value of the volume of a sphere is equal to the numerical value of its surface area, find the radius of the sphere.$
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