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Geometry and Trigonometry / Area and volume Difficulty: Hard

The circumference of the base of a right circular cylinder is 20π20π meters, and the height of the cylinder is 66 meters. What is the volume, in cubic meters, of the cylinder?

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Explanation

Choice C is correct. The volume, VV, of a right circular cylinder is given by the formula V=πr2hV=πr2h, where rr is the radius of the base of the cylinder and hh is the height of the cylinder. It’s given that a right circular cylinder has a height of 66 meters. Therefore, h=6h=6. It's also given that the right circular cylinder has a base with a circumference of 20π20π meters. The circumference, CC, of a circle is given by C=2πrC=2πr, where rr is the radius of the circle. Substituting 20π20π for CC in the formula C=2πrC=2πr yields 20π=2πr20π=2πr. Dividing each side of this equation by 2π2π yields 10=r10=r. Substituting 1010 for rr and 66 for hh in the formula V=πr2hV=πr2h yields V=π(10)2(6)V=π(10)26, or V=600πV=600π. Therefore, the volume, in cubic meters, of the cylinder is 600π600π.

Choice A is incorrect and may result from conceptual or calculation errors.

Choice B is incorrect. This is the lateral surface area, not the volume, of the cylinder.

Choice D is incorrect. This is the result of using the diameter, not the radius, for the value of rr in the formula V=πr2hV=πr2h.