test 39 #12

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dunkin77: Master | Next Rank: 500 Posts; Posts: 269; Joined: Sun Apr 01, 2007 5:41 am

by dunkin77 » Tue May 01, 2007 2:02 am

Hi,

for some reason my answer was C) but the correct answer is D) -- can anyone help?

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Source: Beat The GMAT — Problem Solving | Tue May 01, 2007 2:02 am

Cybermusings: Legendary Member; Posts: 559; Joined: Tue Mar 27, 2007 1:29 am; Thanked: 5 times; Followed by:2 members

by Cybermusings » Tue May 01, 2007 8:53 am

972*pie = 4/3*pie*r^3
972 = 4/3*r^3
(972*3)/4 = r^3
729 = r^3
Thus r = 9

So 4*pie*r^2
=4*81*pie
= 324*pie

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