8th Class Mathematics Mensuration Question Bank Mensuration

  • question_answer Volume of two cubes are in the ratio 1 : 27, find the ratio of their surface areas.

    A)  2 : 9                            

    B)  1 : 9     

    C)  1 : 11                          

    D)  2 : 13

    Correct Answer: B

    Solution :

    (b): \[\frac{{{V}_{1}}}{{{V}_{2}}}=\frac{1}{27}=\frac{{{a}_{1}}^{3}}{{{a}_{2}}^{3}}=\frac{1}{27}\] \[\Rightarrow \frac{{{a}_{1}}}{{{a}_{2}}}=\frac{1}{3}\] (where a,, a, are sides of cubes respectively) \[\Rightarrow \frac{{{a}_{1}}^{2}}{{{a}_{2}}^{2}}=\frac{1}{9}\Rightarrow \frac{6{{a}_{1}}^{2}}{6{{a}_{2}}^{2}}=\frac{1}{9}\] or \[\frac{{{S}_{1}}}{{{S}_{2}}}=\frac{1}{9}\].

adversite


You need to login to perform this action.
You will be redirected in 3 sec spinner