Difference between revisions of "1993 AJHSME Problems/Problem 21"

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<math>\text{(A)}\ 10\% \qquad \text{(B)}\ 30\% \qquad \text{(C)}\ 70\% \qquad \text{(D)}\ 80\% \qquad \text{(E)}\ 100\% </math>
 
<math>\text{(A)}\ 10\% \qquad \text{(B)}\ 30\% \qquad \text{(C)}\ 70\% \qquad \text{(D)}\ 80\% \qquad \text{(E)}\ 100\% </math>
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==Solution==
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If a rectangle had dimensions <math>10 \times 10</math> and area <math>100</math>, then its new dimensions would be <math>12 \times 15</math> and area <math>180</math>. The area is increased by <math>180-100=80</math> or <math>80/100 = \boxed{\text{(D)}\ 80\%}</math>.
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==See Also==
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{{AJHSME box|year=1993|num-b=20|num-a=22}}

Revision as of 23:31, 22 December 2012

Problem

If the length of a rectangle is increased by $20\%$ and its width is increased by $50\%$, then the area is increased by

$\text{(A)}\ 10\% \qquad \text{(B)}\ 30\% \qquad \text{(C)}\ 70\% \qquad \text{(D)}\ 80\% \qquad \text{(E)}\ 100\%$

Solution

If a rectangle had dimensions $10 \times 10$ and area $100$, then its new dimensions would be $12 \times 15$ and area $180$. The area is increased by $180-100=80$ or $80/100 = \boxed{\text{(D)}\ 80\%}$.

See Also

1993 AJHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 20
Followed by
Problem 22
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All AJHSME/AMC 8 Problems and Solutions
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