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Difference between revisions of "2019 AMC 12A Problems/Problem 1"

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==Problem==
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The area of a pizza with radius <math>4</math> is <math>N</math> percent larger than the area of a pizza with radius <math>3</math> inches. What is the integer closest to <math>N</math>?
 
The area of a pizza with radius <math>4</math> is <math>N</math> percent larger than the area of a pizza with radius <math>3</math> inches. What is the integer closest to <math>N</math>?
  
 
<math>\textbf{(A) } 25 \qquad\textbf{(B) } 33 \qquad\textbf{(C) } 44\qquad\textbf{(D) } 66 \qquad\textbf{(E) } 78</math>
 
<math>\textbf{(A) } 25 \qquad\textbf{(B) } 33 \qquad\textbf{(C) } 44\qquad\textbf{(D) } 66 \qquad\textbf{(E) } 78</math>
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==Solution==
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The area of the larger pizza is <math>16\pi</math>, while the area of the smaller pizza is <math>9\pi</math>. Therefore, the larger pizza is <math>\frac{7\pi}{9\pi} \cdot 100\%</math> bigger than the smaller pizza. <math>\frac{7\pi}{9\pi} \cdot 100\% = 77.777....</math>, which is closest to <math>\boxed{\textbf{(E) }78}</math>.
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==Video Solution 1==
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https://youtu.be/SbUEin-OE-k
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~Education, the Study of Everything
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==See Also==
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{{AMC12 box|year=2019|ab=A|before=First Problem|num-a=2}}
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{{MAA Notice}}

Latest revision as of 17:31, 30 October 2022

Problem

The area of a pizza with radius $4$ is $N$ percent larger than the area of a pizza with radius $3$ inches. What is the integer closest to $N$?

$\textbf{(A) } 25 \qquad\textbf{(B) } 33 \qquad\textbf{(C) } 44\qquad\textbf{(D) } 66 \qquad\textbf{(E) } 78$

Solution

The area of the larger pizza is $16\pi$, while the area of the smaller pizza is $9\pi$. Therefore, the larger pizza is $\frac{7\pi}{9\pi} \cdot 100\%$ bigger than the smaller pizza. $\frac{7\pi}{9\pi} \cdot 100\% = 77.777....$, which is closest to $\boxed{\textbf{(E) }78}$.

Video Solution 1

https://youtu.be/SbUEin-OE-k

~Education, the Study of Everything

See Also

2019 AMC 12A (Problems • Answer Key • Resources)
Preceded by
First Problem 		Followed by
Problem 2
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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