8th Class Mathematics Sample Paper Mathematics Sample Paper - 5

  • question_answer
    The area of a rectangular field whose length is twice its breadth is 2450 m2. Find the perimeter of the field.

    Answer:

    Let the breadth of the field be x metres. Then, length of the field be 2x metres.
    Therefore, area of the rectangular field
    = length \[\times \]breadth
    \[=\text{ }\left( 2x \right)\left( x \right)=\left( 2{{x}^{2}} \right)\text{ }{{m}^{2}}\]                   
    Given that area is 2450\[{{m}^{2}}\].
    Therefore, \[2{{x}^{2}}=2450\]
    \[{{x}^{2}}=\frac{2450}{2}\]
    \[x=\sqrt{1225}\]
    or x = 35 m                                                                                                                            
    Hence, breadth = 35 m and length \[35\text{ }\times \text{ }2\]
    = 70 m
    Perimeter to the field \[=2\left( l+b \right)\]
    \[=2\left( 70+35 \right)\text{ }m\]
    \[=2\times 105\text{ }m\]
    = 210 m
               


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