# A Hollow Sphere of External and Internal Diameters 8 Cm and 4 Cm, Respectively is Melted into a Solid Cone of Base Diameter 8 Cm. Find the Height of the Cone. - Mathematics

Sum

A hollow sphere of external and internal diameters 8 cm and 4 cm, respectively is melted into a solid cone of base diameter 8 cm. Find the height of the cone.

#### Solution

We have,

External radius of the hollow sphere, "R"1 = 8/2 =4  "cm"

Internal radius of the hollow sphere, "R"2 = 4/2 = 2  "cm" and

Let the height of the cone, r = 8/2 = 4  "cm"

Let the height of the cone be h.

Now, Volume of the cone = Volume of the hollow sphere

=> 1/3pi"r"^2"h" = 4/3pi"R"_1^3 - 4/3pi"R"_2^3

=> 1/3pi"r"^2"h" = 4/3pi("R"_1^3 - "R"_2^3)

=> "h" = 4/"r"^2 ("R"_1^3 - "R"_2^3)

=> "h" = 4/(4xx4) (4^3 - 2^3)

=>"h" = 1/4(64-8)

=> "h" = 1/4xx56

∴ h = 14 cm

So, the height of the cone is 14 cm.

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#### APPEARS IN

RS Aggarwal Secondary School Class 10 Maths
Chapter 19 Volume and Surface Area of Solids
Exercise | Q 31 | Page 916