ACT · Plane Geometry · Three-dimensional figures
Question act-q-00499
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The question
A cylinder has radius 3 and height 8. What is its volume, in terms of π?
- 48π
- 72π
- 17π
- 24π
Show answer & worked solution
Answer: 72π
Worked solution. Volume of a cylinder is πr²h. Here r = 3 and h = 8, so V = π × 3² × 8 = 72π.
Why each wrong choice is wrong. The 2πr × h distractor confuses lateral surface area with volume. Memorize both formulas separately.
Test-day tactic. Volume formula for any prism or cylinder: base area × height. For a cylinder, base area is πr².
About this question type
Items test volume and surface area for the standard solids: rectangular prisms, cylinders, cones, spheres, and pyramids.
You will see a question shaped like this one on roughly every other official ACT form, typically at a moderate position in the section — solidly within the range that separates a 600-band student from a 700-band student. Treat any miss in this subtopic as a signal to drill the subtopic page before you do another full practice test.