8th Class Mathematics Sample Paper Mathematics Sample Paper - 2

  • question_answer
                               Find the volume of a cube whose surface area is 150 m2.

    Answer:

    Since, surface area of cube
    \[=\text{ }150\text{ }{{m}^{2}}\]
    Let the length of each edge = a
    Then, surface area of cube = 6a2
    According to problem,
    \[6{{a}^{2}}=150\]
    or
    \[{{a}^{2}}=\frac{150}{6}=25\]
    or
    \[{{a}^{2}}=\text{ }25\]
    \[\Rightarrow a=\text{ }\sqrt{25\text{ }}=\text{ }\sqrt{5\times 5}\]
    \[\Rightarrow a=\text{ }5\text{ }m\]
    We know that,
    Volume of cube
    \[={{a}^{3}}\]
    cubic metre
    Therefore,
    Volume of cube
    \[=\text{ }{{5}^{3}}\]
    \[=\text{ }5\text{ }\times \text{ }5\text{ }\times \text{ }5\]
    \[=\text{ }125\text{ }{{m}^{3}}\]
                           


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