Khan/khan-exercises — Issue #9885: Solid geometry - Solid Geometry (Cylinder Surface)
Author: KhanBugz
Created: 2011-12-30 16:42:21+00:00
State: open
Labels: firefox, win7, wrong-or-unclear

Reporter: fantasycomedian@gmail.com

What is the surface area of a cylinder with base radius 3 and height 6?

Khan Academy Answer: 54 pi

Real Answer (it seems): 72 pi

3 (radius) X 3 = 9 X 2 (top and bottom) = 18/2 = 9 X 6 = 54 + 18 = 72 pi

[solid_geometry.html?seed=36&problem=cylinder-T](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/solid_geometry.html?seed=36&problem=cylinder-T&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/solid_geometry.html?seed=36&problem=cylinder-T&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5C%2272%20pi%5C%22%22%2C4%5D%2C%5B%22hint-activity%22%2C%220%22%2C26%5D%2C%5B%22hint-activity%22%2C%220%22%2C29%5D%2C%5B%22hint-activity%22%2C%220%22%2C29%5D%2C%5B%22hint-activity%22%2C%220%22%2C29%5D%2C%5B%22hint-activity%22%2C%220%22%2C30%5D%5D)

["72 pi","72 pi"]

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0.1) Gecko/20100101 Firefox/8.0.1

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