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# RD Chapter 21- Surface Areas and Volume of a Sphere Ex-VSAQS Interview Questions Answers

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Question 1 : Find the surface area of a sphere of radius 14 cm.

Radiusof a sphere (r) = 14 cm
Surface area = 4πr2 = 4 x x 14 x 14 cm2

= 2464 cm3

Question 2 : Find the total surface afea of a hemisphere of radius 10 cm.

Radius of hemisphere (r) = 10 cm
∴ Total surface area = 3πr2

Question 3 : Find the radius of a sphere whose surface area is 154 cm2.

Answer 3 : Surface area of a sphere = 154 cm2

Question 4 : The hollow sphere, in which the circus motor cyclist performs his stunts, has a diameter of 7 m. Find the area available to the motor cyclist for riding.

Answer 4 : Diameter of hollow sphere = 7 m

Question 5 : Find the volume of a sphere whose surface area is 154 cm2.

Answer 5 : Surface area of a sphere = 154 cm2

Question 6 : How many spherical bullets can be made out of a solid cube of lead whose edge measures 44 cm, each bullet being 4 cm in diameter?

Answer 6 : Edge of a solid cube = 44 cm
Volume = a2 =(44)2 cm2
= 44 × 44 × 44 cm3
Diameter of a spherical bullet = 4 cm

Question 7 : If a sphere of radius 2r has the same volume as that of a cone with circular base of radius r, then find the height of the cone.

Question 8 : If a hollow sphere of intefnal 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.

Answer 8 : Internal diameter of a hollow sphere = 4cm
Internal radius = 4/2 = 2 cm
Similarly the outer radius (R) =
8/2 = 4 cm
Volume of melted used inhollow sphere

Question 9 : The surface area of a sphere of radius 5 cm is five times the area of the curved surface of a cone of radius 4 cm. Find the height of the cone.

Surface area = 4πr2
= 4π x 5 x 5 = 100π cm2
Radius of cone (r1) = 4 cm

Question 10 : If a sphere is inscribed in a cube, find the ratio of the volume of cube to the volume of the sphere.

Answer 10 : Let edge of a cube = a
Then its volume = a3
A sphere is inscribed inthe cube
Diameter of sphere = a

krishan