SSC Sample Paper SSC CGL - Sample Paper-25

  • question_answer
    If the volumes of two cubes are in the ratio 27 : 64 and then the ratio of their total surface area is

    A) 27 : 64 

    B) 3 : 4            

    C) 9 : 16

    D) 3 : 8

    Correct Answer: C

    Solution :

    \[\because \]       \[\frac{{{V}_{1}}}{{{V}_{2}}}=\frac{27}{64}\] Let \[{{a}_{1}}\] and \[{{a}_{2}}\] are the sides of two cubes. \[\therefore \]      \[\frac{a_{1}^{3}}{a_{2}^{3}}=\frac{27}{64}={{\left( \frac{3}{4} \right)}^{3}}\] \[\Rightarrow \]   \[{{a}_{1}}:{{a}_{2}}=3:4\] \[\therefore \] Ratio of their total surface area \[=\frac{6a_{1}^{2}}{6a_{2}^{2}}\]             \[={{\left( \frac{{{a}_{1}}}{{{a}_{2}}} \right)}^{2}}={{\left( \frac{3}{4} \right)}^{2}}\]             \[=9:16\]                      


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