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Two companies working together can clear a parcel of land in 22 hours. Working alone, it would take Company A 2 hours longer to clear the land than it would Company B. How long would it take Company B to clear the parcel of land alone? (Round your answer to the nearest tenth.)
 Jun 28, 2015

Best Answer 

 #1
avatar+128089 
+5

Let x be the time it takes in hours for B to clear the land......then....the amount of work that B can do in one hr = 1/x

Let x + 2 be the time in hours for A to clear the land..and the amount of work done in one hour by A is         1/(x +2)

 

(Amt done in one hour by each) * 22 hours = 1 whole job done.....or, mathematically......

 

[1/x  + 1/(x+2)] *22   =  1       simplify  by getting a common denominator on the left

 

[(x + 2 + x)] *22 / [(x(x + 2)]  = 1   multiply both sides by the reciprocal of .... 22 / [(x(x + 2)]       

 

2x + 2   =  [x(x + 2)] / 22        multiply both sides by 22....expand the right side

 

44x + 44  = x^2 + 2x     simplify some more

 

x^2 - 42x - 44  = 0    and using the onsite calculator we have

 

$${{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{42}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{44}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{21}}{\mathtt{\,-\,}}{\sqrt{{\mathtt{485}}}}\\
{\mathtt{x}} = {\sqrt{{\mathtt{485}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{21}}\\
\end{array} \right\} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = -{\mathtt{1.022\: \!715\: \!545\: \!545\: \!240\: \!5}}\\
{\mathtt{x}} = {\mathtt{43.022\: \!715\: \!545\: \!545\: \!240\: \!5}}\\
\end{array} \right\}$$

So...it would take "B" about 43 hours to clear the land working alone......[rounded to the nearest tenth]

 

 

 Jun 28, 2015
 #1
avatar+128089 
+5
Best Answer

Let x be the time it takes in hours for B to clear the land......then....the amount of work that B can do in one hr = 1/x

Let x + 2 be the time in hours for A to clear the land..and the amount of work done in one hour by A is         1/(x +2)

 

(Amt done in one hour by each) * 22 hours = 1 whole job done.....or, mathematically......

 

[1/x  + 1/(x+2)] *22   =  1       simplify  by getting a common denominator on the left

 

[(x + 2 + x)] *22 / [(x(x + 2)]  = 1   multiply both sides by the reciprocal of .... 22 / [(x(x + 2)]       

 

2x + 2   =  [x(x + 2)] / 22        multiply both sides by 22....expand the right side

 

44x + 44  = x^2 + 2x     simplify some more

 

x^2 - 42x - 44  = 0    and using the onsite calculator we have

 

$${{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{42}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{44}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{21}}{\mathtt{\,-\,}}{\sqrt{{\mathtt{485}}}}\\
{\mathtt{x}} = {\sqrt{{\mathtt{485}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{21}}\\
\end{array} \right\} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = -{\mathtt{1.022\: \!715\: \!545\: \!545\: \!240\: \!5}}\\
{\mathtt{x}} = {\mathtt{43.022\: \!715\: \!545\: \!545\: \!240\: \!5}}\\
\end{array} \right\}$$

So...it would take "B" about 43 hours to clear the land working alone......[rounded to the nearest tenth]

 

 

CPhill Jun 28, 2015

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