6th Class Mathematics Mensuration Question Bank Mensuration Basics

  • question_answer
    If the ratio of circumference of two circle is \[4:9,\] what is the ratio of their areas?

    A) \[9:4\]                          

    B) \[16:81\]

    C) \[4:9\]                          

    D) \[2:3\]

    Correct Answer: B

    Solution :

    \[\left. \begin{align}   & Circle-1:{{C}_{1}}=2\pi {{r}_{1}} \\  & Circle-2:{{C}_{2}}=2\pi {{r}_{2}} \\ \end{align} \right\}\]Now, \[a\frac{2\pi {{r}_{1}}}{2\pi {{r}_{2}}}=\frac{{{r}_{1}}}{{{r}_{2}}}=\frac{4}{9};\]Area ratio \[\frac{{{A}_{1}}}{{{A}_{2}}}=\frac{\pi {{r}_{1}}^{2}}{\pi {{r}_{2}}^{2}}={{\left( \frac{{{r}_{1}}}{{{r}_{2}}} \right)}^{2}}\] \[={{\left( \frac{4}{9} \right)}^{2}}=\frac{16}{81}\]


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