Difference between revisions of "2007 AMC 12B Problems/Problem 8"

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==Problem==
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#REDIRECT [[2007 AMC 10B Problems/Problem 12]]
 
 
Tom's age is <math>T</math> years, which is also the sum of the ages of his three children. His age <math>N</math> years ago was twice the sum of their ages then. What is <math>T/N</math> ?
 
 
 
<math>\mathrm {(A)} 2</math>  <math>\mathrm {(B)} 3</math>  <math>\mathrm {(C)} 4</math>  <math>\mathrm {(D)} 5</math>  <math>\mathrm {(E)} 6</math>
 
 
 
==Solution==
 
 
 
<math>T=a+b+c</math>
 
 
 
<math>T-N=2(a-N+b-N+c-N)=2(a+b+c)-6N=2T-6N</math>
 
 
 
<math>2T-6N=T-N</math>
 
 
 
<math>T=5N</math>
 
 
 
<math>T/N=5 \Rightarrow \mathrm {(D)}</math>
 
 
 
==See Also==
 
 
 
{{AMC12 box|year=2007|ab=B|num-b=7|num-a=9}}
 

Revision as of 15:27, 5 June 2011