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| − | ==Problem==
| + | #REDIRECT [[2007 AMC 10B Problems/Problem 14]] |
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| − | Some boys and girls are having a car wash to raise money for a class trip to China. Initially <math>40</math>% of the group are girls. Shortly thereafter two girls leave and two boys arrive, and then <math>30</math>% of the group are girls. How many girls were initially in the group?
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| − | <math>\mathrm {(A)} 4</math> <math>\mathrm {(B)} 6</math> <math>\mathrm {(C)} 8</math> <math>\mathrm {(D)} 10</math> <math>\mathrm {(E)} 12</math>
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| − | ==Solution==
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| − | First, determine the total number of people in the group.
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| − | <math>2=(40/100-30/100)t</math>
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| − | <math>t=200/10=20</math>
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| − | Now find the original number of girls:
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| − | <math>40/100t = 800/100 = 8</math>
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| − | So, there are 8 girls, <math>\Rightarrow \fbox{C}</math>
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| − | ==See Also==
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| − | {{AMC12 box|year=2007|ab=B|num-b=9|num-a=11}}
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