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Difference between revisions of "2010 AMC 10A Problems/Problem 1"
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== Problem 1 ==
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Mary’s top book shelf holds five books with the following widths, in centimeters: <math>6</math>, <math>\dfrac{1}{2}</math>, <math>1</math>, <math>2.5</math>, and <math>10</math>. What is the average book width, in centimeters?
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<math>
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\mathrm{(A)}\ 1
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\qquad
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\mathrm{(B)}\ 2
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\qquad
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\mathrm{(C)}\ 3
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\qquad
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\mathrm{(D)}\ 4
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\qquad
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\mathrm{(E)}\ 5
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</math>
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==Solution==
 
==Solution==
  

Revision as of 15:28, 20 December 2010

Problem 1

Mary’s top book shelf holds five books with the following widths, in centimeters: $6$, $\dfrac{1}{2}$, $1$, $2.5$, and $10$. What is the average book width, in centimeters?

$\mathrm{(A)}\ 1 \qquad \mathrm{(B)}\ 2 \qquad \mathrm{(C)}\ 3 \qquad \mathrm{(D)}\ 4 \qquad \mathrm{(E)}\ 5$

Solution

To find the average, we add up the widths $6$, $\dfrac{1}{2}$, $1$, $2.5$, and $10$, to get a total sum of $20$. Since there are $5$ books, the average book width is $\frac{20}{5}=4$ The answer is $\boxed{D}$.

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