Difference between revisions of "1959 AHSME Problems/Problem 9"

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== Problem ==
 
== Problem ==
  
A farmer divides his herd of <math>n</math>cows among his four sons so that one son gets one-half the herd, a second son, one-fourth, a third son, one-fifth, and the fourth son, <math>7</math> cows. Then <math>n</math> is: <math>\textbf{(A)}\ 80 \qquad\textbf{(B)}\ 100\qquad\textbf{(C)}\ 140\qquad\textbf{(D)}\ 180\qquad\textbf{(E)}\ 240</math>
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A farmer divides his herd of <math>n</math> cows among his four sons so that one son gets one-half the herd, a second son, one-fourth, a third son, one-fifth, and the fourth son, <math>7</math> cows. Then <math>n</math> is: <math>\textbf{(A)}\ 80 \qquad\textbf{(B)}\ 100\qquad\textbf{(C)}\ 140\qquad\textbf{(D)}\ 180\qquad\textbf{(E)}\ 240</math>
  
 
== Solution ==
 
== Solution ==
  
The first three sons get <math>\frac{1}{2}+\frac{1}{4}+\frac{1}{5}=\frac{19}{20}</math> of the herd, so that the fourth son should get <math>\frac{1}{20}</math> of it. But the fourth son gets <math>7</math> cows, so the size of the herd is <math>n=\frac{7}{\frac{1}{20}} = 140</math>. Then our answer is <math>\boxed{C}</math>, and we are done.
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The first three sons get <math>\frac{1}{2}+\frac{1}{4}+\frac{1}{5}=\frac{19}{20}</math> of the herd, so that the fourth son should get <math>\frac{1}{20}</math> of it. But the fourth son gets <math>7</math> cows, so the size of the herd is <math>n=\frac{7}{\frac{1}{20}} = 140</math>. Then our answer is <math>\fbox{\textbf{(C) 140}}</math>.
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==See also==
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{{AHSME 50p box|year=1959|num-b=8|num-a=10}}
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{{MAA Notice}}
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[[Category:Introductory Algebra Problems]]

Revision as of 12:08, 21 July 2024

Problem

A farmer divides his herd of $n$ cows among his four sons so that one son gets one-half the herd, a second son, one-fourth, a third son, one-fifth, and the fourth son, $7$ cows. Then $n$ is: $\textbf{(A)}\ 80 \qquad\textbf{(B)}\ 100\qquad\textbf{(C)}\ 140\qquad\textbf{(D)}\ 180\qquad\textbf{(E)}\ 240$

Solution

The first three sons get $\frac{1}{2}+\frac{1}{4}+\frac{1}{5}=\frac{19}{20}$ of the herd, so that the fourth son should get $\frac{1}{20}$ of it. But the fourth son gets $7$ cows, so the size of the herd is $n=\frac{7}{\frac{1}{20}} = 140$. Then our answer is $\fbox{\textbf{(C) 140}}$.

See also

1959 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 8
Followed by
Problem 10
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All AHSME Problems and Solutions

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