EXERCISE - A
1) The diameter of a sphere is 7cm. Calculate:
A) the surface area of the sphere. 154cm²
B) volume of the sphere to 2 decimal places. 279.67cm³
) The diameter of the sphere is 21cm. Calculate its surface area and the the volume. 1386cm², 4851cm³
2) Find the volume and surface area of sphere whose
a) radius 21/4 cm. 606.375cm³, 346.5cm²
b) diameter 14 cm. 1437.33cm³, 616cm²
3) Find the volume and surface area of the sphere of radius 5.6cm. 735.3cm³, 394.24cm²
2) The volume of a sphere is 38π cm². Find the radius and the surface area of the sphere. 3, 392/7
5) Volume of a sphere is 38808cm³, find its diameter and surface area. 42, 5544
) Find the surface area of a sphere whose volume is 4851m³. 1386m²
) The surface area of sphere is 616 cm². Calculate its radius and volume. 7, 1437.33cm³
) ) The surface area of sphere is 346.5m cm². Find its radius and volume. 5.25m, 606.6cm³
6) Find the total surface area of a hemisphere of radius 20cm. (Take π=3.14). 3770.4
) Find the volume and the total surface area of a hemisphere of radius 3.5cm. 89.83cm³, 115.5cm²
7) The total surface area of a hemisphere is 462cm². Find the diameter and volume of the hemisphere. 14, 718.67
3) the surface area of a sphere is 1256cm². It is cut into two hemispheres. Calculate:
A) radius of the sphere. 10
B) total surface area of hemisphere. 942
C) volume of a hemisphere correct to decimal places. 2093.33
16) The external and internal diameter of a hemispherical bowl are 17cm and 15cm respectively. Find the cost of polishing it all over at 25 paise per cm? 214.50
) A hollow copper ball has an external diameter 12cm and a thickness of 0.1 cm. Find
a) the outer surface of the area of the ball. 452.57cm²
b) the weight of the ball, if 1 cm³ of copper weight 8.8gms. 391.69gm
) The outer diameter the shell (spherical) is 10 cm and the inner diameter is 9 cm. Find the volume of the metal contained in the shell. 141.95cm³
) The internal and external diameters of a hollow hemispherical vessel are 21 cm and 25.2cm respectively. The cost of printing 1 cm² of the surface is 50 paise . Find the total cost to paint the vessels all over. Rs921.70
4) If the number of square centimetre on the surface of a sphere is equal to the number of cubic centimetres in its volume, find the diameter of the sphere. 6
)
9) how many lead balls each of radius 1cm can be made from a sphere of radius 2cm ? 8
10) How many balls each of radius 1cm can be made by a melting a bigger ball whose diameter is 8 cm ? 64
) Spherical ball of lead has been melted made into identical smaller balls each with radius equals to half the radius of the original one. How many such balls can be made ? 8
) How many balls each of radius 1 cm can be made by melting a big ball with diameter is 8 cm. 64
) 8 metallic spheres; each of radius 2mm, are melted and casted into a single sphere. Find the radius of the new sphere. 4mm
) A solid metal sphere is cut through its centre into 2 equal parts. If the diameter is 7/2 cm, find the total surface area, of each part correct to two decimal places. 28.88cm²
) The volume of one sphere is 27 times that of another sphere . Calculate the ratio of their
a) radius
b) surface areas.
22) the radius of a sphere is doubled. Find the increase percent in the surface area. 300
23) the radius of a sphere is increased by 50%. Find the increase percent in its volume. 237.5%
30) A spherical metallic ball of radius 3 cm is melted and recast into three spherical balls. The radii of two of these balls are 2.5 cm and 2cm respectively. Find the radius of the third ball. 1.5
) A Spherical ball of lead has been melted and made into smaller balls of half the radius of the original one. How many such balls can be made ? Find the ratio of the total surface of all the smaller balls to that of the original one. 8, 2:1
) A Sphere of lead diameter 6 m is melted and recast into three spherical balls. The diameters of these are 3 m and 4 m respectively. Find the diameter of the third one. 5cm
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