Difference between revisions of "1985 AJHSME Problems/Problem 6"

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==Solution==
 
==Solution==
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We could solve the first equation for the thickness of one sheet of paper, and divide into the 2nd equation (which is one way to do the problem), but there are other ways, too.
 
We could solve the first equation for the thickness of one sheet of paper, and divide into the 2nd equation (which is one way to do the problem), but there are other ways, too.
  
Let's say that <math>\frac{500 sheets of paper}{5 cm} = 1</math>. So by multiplying <math>7.5 cm</math> by this fraction, we SHOULD get the number of sheets in 7.5 cm. Solving gets...
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Let's say that <math>\frac{500 \text{ sheets of paper}}{5 \text{ cm}} = 1</math>. So by multiplying <math>7.5 \text{ cm}</math> by this fraction, we SHOULD get the number of sheets in 7.5 cm. Solving gets
  
<math>\frac{7.5 \times 500}{5} = 7.5 \times 100 = 750 sheets</math>
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<cmath>\begin{align*}
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\frac{7.5 \times 500}{5} &= 7.5 \times 100 \\
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&= 750 sheets \\
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\end{align*}</cmath>
  
<math>750</math> is (D)
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<math>750</math> is <math>\boxed{\text{D}}</math>
  
 
==See Also==
 
==See Also==
  
 
[[1985 AJHSME Problems]]
 
[[1985 AJHSME Problems]]

Revision as of 21:36, 12 January 2009

Problem

A ream of paper containing $500$ sheets is $5$ cm thick. Approximately how many sheets of this type of paper would there be in a stack $7.5$ cm high?

$\text{(A)}\ 250 \qquad \text{(B)}\ 550 \qquad \text{(C)}\ 667 \qquad \text{(D)}\ 750 \qquad \text{(E)}\ 1250$

Solution

We could solve the first equation for the thickness of one sheet of paper, and divide into the 2nd equation (which is one way to do the problem), but there are other ways, too.

Let's say that $\frac{500 \text{ sheets of paper}}{5 \text{ cm}} = 1$. So by multiplying $7.5 \text{ cm}$ by this fraction, we SHOULD get the number of sheets in 7.5 cm. Solving gets

\begin{align*} \frac{7.5 \times 500}{5} &= 7.5 \times 100 \\ &= 750 sheets \\ \end{align*}

$750$ is $\boxed{\text{D}}$

See Also

1985 AJHSME Problems