NTSE Sample Paper NTSE SAT Practice Test-10

  • question_answer
    The volume of a cuboid whose sides are in the ratio of 1 : 2 : 4 is the same as that of a cube. What is the ratio of length of diagonal of cuboid to that of a cube?

    A) \[\sqrt{7}:1\]                 

    B) \[\sqrt{7}:2\]

    C) \[\sqrt{7}:3\]                 

    D) \[\sqrt{7}:4\]

    Correct Answer: B

    Solution :

    [b] \[x\times 2x\times 4x={{y}^{3}}\] or \[8{{x}^{3}}={{y}^{3}}\] or \[y=2x\] \[\therefore \,\,\,\,\,\,\frac{Diagonal\text{ }of\text{ }cuboid}{Diagonal\text{ }of\text{ }cube}\] \[=\frac{\sqrt{{{(4x)}^{2}}+{{(2x)}^{2}}+{{x}^{2}}}}{y\sqrt{3}}=\frac{\sqrt{21{{x}^{2}}}}{y\sqrt{3}}=\frac{\sqrt{7}}{2}\]


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