# If a hollow sphere of internal and external diameters 4 cm and 8 cm respectively melted into a cone of base diameter 8 cm, then find the height of the cone. - Mathematics

Short Note

If a hollow sphere of internal and external diameters 4 cm and 8 cm respectively melted into a cone of base diameter 8 cm, then find the height of the cone.

#### Solution

In the given problem, we have a hollow sphere of given dimensions;

Internal diameter of the sphere (d) = 4 cm

External diameter of the sphere (D) = 8 cm

Now, the given sphere is molded into a cone,

Diameter of the base of cone (dc) = 8 cm

Now, the volume of hollow sphere is equal to the volume of the cone.

So, let the height of cone = cm

Therefore, we get

Volume of cone = the volume of hollow sphere

(1/3) pi ((d_c)/2)^2 h = (4/3) pi ((D/2)^3 -(d/2)^3)

(1/3) pi (8/2)^2 (h) = (4/3) pi ((8/2)^3 -(4/2)^3)

(1/3)pi (4)^2 (h) = (4/3) pi (64-8)

Further, solving for h,

 h = ((4/3) pi (56))/((1/3) pi (16))

h = ((4)(56))/((16))

h = 14 cm

So, height of the cone is 14 cm

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#### APPEARS IN

RD Sharma Mathematics for Class 9
Chapter 21 Surface Areas and Volume of a Sphere
Q 8 | Page 25