GRE Quantitative Reasoning Practice Exam

The main idea is the curved surface area of a hemisphere. A full sphere has surface area 4πr^2, so the curved surface of a hemisphere is half of that: 2πr^2. With radii r = 4, the curved surface area is S = 2π(4)^2 = 2π·16 = 32π. Numerically, 32π ≈ 100.53. So the value you’re looking for is about 100.53.