ACT Math · Area and volume
A cylinder has radius 4 and height 9. Which value is closest to its total surface area?
A cylinder has radius 4 and height 9. Which value is closest to its total surface area?
Answer and explanation
Answer: D: 327
The total surface area of a closed cylinder includes two circular bases and the curved side: , choice D. Choice A () is the lateral surface only, , and leaves out both bases. Choice B () is , which includes only one base. Choice C () is , which adds more area than the cylinder has. The question asks for the total surface, so count both bases. Sketching the net of a cylinder helps.
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