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9th Class Mathematics Surface Areas and Volumes Question Bank Surface Areas and Volumes

  • question_answer
    If each edge of a cube is increased by 50%, what is the percentage increase in its surface area?

    A)  50%                           

    B)    75%               

    C)    100%                         

    D)    125%             

    Correct Answer: D

    Solution :

    The edges of cube is ?a? units. The edge is increased by 50% \[=a+\frac{a}{2}=\frac{3a}{2}\] \[\therefore \]Surface area \[=6{{a}^{2}}=\frac{27{{a}^{2}}}{2}\] \[\therefore \]Percentage increase of surface area \[=\frac{\left( \frac{27{{a}^{2}}}{2}-6{{a}^{2}} \right)}{6{{a}^{2}}}\times 100%=125%\]


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