Difference between revisions of "2003 AMC 12B Problems/Problem 13"

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Let <math>r</math> be the common radius of the sphere and the cone, and <math>h</math> be the cone’s height. Then
 
Let <math>r</math> be the common radius of the sphere and the cone, and <math>h</math> be the cone’s height. Then
 
<cmath>75\% \cdot \left(\frac 43 \pi r^3\right) = \frac 13 \pi r^2 h \Longrightarrow h = 3r</cmath>
 
<cmath>75\% \cdot \left(\frac 43 \pi r^3\right) = \frac 13 \pi r^2 h \Longrightarrow h = 3r</cmath>
Thus <math>h:r = 3:1</math>.
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Thus <math>h:r = 3:1</math> and the answer is <math>\boxed{B}</math>.
  
 
== See also ==
 
== See also ==
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[[Category:Introductory Algebra Problems]]
 
[[Category:Introductory Algebra Problems]]
 
[[Category:Introductory Geometry Problems]]
 
[[Category:Introductory Geometry Problems]]
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{{MAA Notice}}

Latest revision as of 14:20, 17 October 2016

Problem

An ice cream cone consists of a sphere of vanilla ice cream and a right circular cone that has the same diameter as the sphere. If the ice cream melts, it will exactly fill the cone. Assume that the melted ice cream occupies $75\%$ of the volume of the frozen ice cream. What is the ratio of the cone’s height to its radius?

$\mathrm{(A)}\ 2:1 \qquad\mathrm{(B)}\ 3:1 \qquad\mathrm{(C)}\ 4:1 \qquad\mathrm{(D)}\ 16:3 \qquad\mathrm{(E)}\ 6:1$

Solution

Let $r$ be the common radius of the sphere and the cone, and $h$ be the cone’s height. Then \[75\% \cdot \left(\frac 43 \pi r^3\right) = \frac 13 \pi r^2 h \Longrightarrow h = 3r\] Thus $h:r = 3:1$ and the answer is $\boxed{B}$.

See also

2003 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
Problem 12
Followed by
Problem 14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions

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