Difference between revisions of "2013 AMC 10A Problems/Problem 2"

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==Problem==
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Alice is making a batch of cookies and needs <math>2\frac{1}{2}</math> cups of sugar.  Unfortunately, her measuring cup holds only <math>\frac{1}{4}</math> cup of sugar.  How many times must she fill that cup to get the correct amount of sugar?
 
Alice is making a batch of cookies and needs <math>2\frac{1}{2}</math> cups of sugar.  Unfortunately, her measuring cup holds only <math>\frac{1}{4}</math> cup of sugar.  How many times must she fill that cup to get the correct amount of sugar?
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<math> \textbf{(A)}\ 8 \qquad\textbf{(B)}\ 10  \qquad\textbf{(C)}\ 12 \qquad\textbf{(D)}\ 16 \qquad\textbf{(E)}\ 20 </math>
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==Solution==
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To get how many cups we need, we realize that we simply need to divide the number of cups needed by the number of cups collected in her measuring cup each time.  Thus, we need to evaluate the fraction <math>\frac{2\frac{1}{2}}{\frac{1}{4}}</math>.  Simplifying, this is equal to <math>\frac{5}{2}(4) = 10</math>, <math>\textbf{(B)}</math>.

Revision as of 19:44, 7 February 2013

Problem

Alice is making a batch of cookies and needs $2\frac{1}{2}$ cups of sugar. Unfortunately, her measuring cup holds only $\frac{1}{4}$ cup of sugar. How many times must she fill that cup to get the correct amount of sugar?

$\textbf{(A)}\ 8 \qquad\textbf{(B)}\ 10  \qquad\textbf{(C)}\ 12 \qquad\textbf{(D)}\ 16 \qquad\textbf{(E)}\ 20$

Solution

To get how many cups we need, we realize that we simply need to divide the number of cups needed by the number of cups collected in her measuring cup each time. Thus, we need to evaluate the fraction $\frac{2\frac{1}{2}}{\frac{1}{4}}$. Simplifying, this is equal to $\frac{5}{2}(4) = 10$, $\textbf{(B)}$.