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Q26.    A man wants to cut three lengths from a single piece of board of length 91cm. The second length is to be 3cm longer than the shortest and the third length is to be twice as long as the shortest. What are the possible lengths of the shortest board if the third piece is to be at least 5cm longer than the second?

[Hint: If x is the length of the shortest board, then x , (x + 3)and 2x are the lengths of the second and third piece, respectively. Thus,x + (x + 3) + 2x \leq 91 and 2x \geq (x + 3) + 5].

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Let  x is the length of the shortest board,

then  (x + 3)and 2x are the lengths of the second and third piece, respectively.

The  man wants to cut three lengths from a single piece of board of length 91cm.

Thus,x + (x + 3) + 2x \leq 91 

            4x+3\leq 91

   \Rightarrow \, \, \, \, 4x\leq 91-3

     \Rightarrow \, \, \, \, 4x\leq 88

    \Rightarrow \, \, \, \, x\leq \frac{88}{4}

     \Rightarrow \, \, \, \, x\leq 22

if the third piece is to be at least 5cm longer than the second, than  

           2x \geq (x + 3) + 5

\Rightarrow \, \, \, \, 2x\geq x+8

\Rightarrow \, \, \, \, 2x-x\geq 8

\Rightarrow \, \, \, \, x\geq 8

   

We conclude that  \, \, \, \, x\geq 8  and   \, \, \, \, x\leq 22.

Thus , 8\leq x\leq 22.

Hence, the length of the shortest board is greater than equal to 8 cm and less than equal to 22 cm.

 

 

 

 

 

 

Posted by

seema garhwal

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