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8th Class Mathematics Mensuration Question Bank Mensuration

  • question_answer
    A hollow sphere of internal and external radii respectively, 2cm and 4cm is melted into a solid cone of base radius 4 cm. Find the height of the cone.

    A) 12cm                          

    B) 7cm

    C) 14cm            

    D) 21cm                    

    Correct Answer: C

    Solution :

    Volume of material of hollow sphere = Volume of external sphere - volume of internal sphere \[=2\pi rh\] Now, let the height of the cone be h cm. Volume of cone = Volume of material of hollow sphere \[=2\pi r(h+r)\] \[=\pi rl.\] \[l=\sqrt{{{h}^{2}}+{{r}^{2}}}\]    


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