Nokea
A water fountain has a spherical base with a diameter of 50cm and a cylindrical body with a diameter of 30cm and a height of 80cm. What is the total surface area of the fountain (excluding the water surface)?
Correct Answer: C
Rationale: To find the total surface area of the fountain, we first calculate the surface area of the sphere and the cylinder separately.
For the sphere:
- Radius = Diameter / 2 = 50 / 2 = 25 cm
- Surface area of a sphere = 4πr² = 4 x π x 25² = 500π cm²
For the cylinder:
- Radius = Diameter / 2 = 30 / 2 = 15 cm
- Surface area of a cylinder = 2πrh + 2πr² = 2 x π x 15 x 80 + 2 x π x 15² = 240π + 450π = 690π cm²
Total surface area = Surface area of sphere + Surface area of cylinder
= 500π + 690π = 1190π cm²
≈ 5486 sq cm. Therefore, the correct answer is C.
Choice A (3142 sq cm) is incorrect as it is much smaller than the correct answer. Choices B and D are also incorrect as they do not reflect the accurate calculation of the total surface area of the fountain.