MediumMath· Geometry and Trigonometry· Area and volume· MCQ
A right circular cylinder has a volume of . If the height of the cylinder is 5, what is the radius of the cylinder?
A
3
B
4.5
C
9
D
40
Correct answer: A
Explanation
Choice A is correct. The volume of a right circular cylinder with a radius of r is the product of the area of the base, , and the height, h. The volume of the right circular cylinder described is and its height is 5. If the radius is r, it follows that . Dividing both sides of this equation by yields . Taking the square root of both sides yields or . Since r represents the radius, the value must be positive. Therefore, the radius is 3.
Choice B is incorrect and may result from finding that the square of the radius is 9, but then from dividing 9 by 2, rather than taking the square root of 9. Choice C is incorrect. This represents the square of the radius. Choice D is incorrect and may result from solving the equation for , not r, by dividing by on both sides and then by subtracting, not dividing, 5 from both sides.
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id cb_question_bank:06f8d61b-8ecf-4d83-8cb4-b0a411707558 · question f67e4efc · IBN 027063-DC
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