Difference between revisions of "2004 AMC 12B Problems/Problem 1"

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==Problem==
 
==Problem==
Each row of the Misty Moon Amphitheater has 33 seats. Rows 12 through 22 are reserved for a youth club. How many seats are reserved for this club?
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At each basketball practice last week, Jenny made twice as many free throws as she made at the previous practice. At her fifth practice she made <math>48</math> free throws. How many free throws did she make at the first practice?
  
<math>\mathrm {(A)} 297 \qquad \mathrm {(B)} 330 \qquad \mathrm {(C)} 363 \qquad \mathrm {(D)} 396 \qquad \mathrm {(E)} 726</math>
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<math>\mathrm {(A)} 3 \qquad \mathrm {(B)} 6\qquad \mathrm {(C)} 9 \qquad \mathrm {(D)} 12 \qquad \mathrm {(E)} 15</math>
  
 
==Solution==
 
==Solution==
There are <math>22-12+1=11</math> rows reserved for the youth club. At <math>33</math> seats per row, there are <math>33\cdot 11</math> seats reserved.
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Each day Jenny makes half as many free throws as she does at the next practice. Hence on the fourth day she made <math>\frac{1}{2} \cdot 48 = 24</math> free throws, on the third <math>12</math>, on the second <math>6</math>, and on the first <math>3 \Rightarrow \mathrm{(A)}</math>.
 
 
 
 
<math>33\cdot 11=363\Longrightarrow (\mathrm{C})</math>
 
  
 
==See Also==
 
==See Also==
 
{{AMC12 box|year=2004|ab=B|before=First Question|num-a=2}}
 
{{AMC12 box|year=2004|ab=B|before=First Question|num-a=2}}
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[[Category:Introductory Algebra Problems]]

Revision as of 18:03, 10 February 2008

Problem

At each basketball practice last week, Jenny made twice as many free throws as she made at the previous practice. At her fifth practice she made $48$ free throws. How many free throws did she make at the first practice?

$\mathrm {(A)} 3 \qquad \mathrm {(B)} 6\qquad \mathrm {(C)} 9 \qquad \mathrm {(D)} 12 \qquad \mathrm {(E)} 15$

Solution

Each day Jenny makes half as many free throws as she does at the next practice. Hence on the fourth day she made $\frac{1}{2} \cdot 48 = 24$ free throws, on the third $12$, on the second $6$, and on the first $3 \Rightarrow \mathrm{(A)}$.

See Also

2004 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
First Question
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