Volume and Surface Area
Practice Questions - Volume and Surface Area
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Q1) The edge of a cube is 15 cm. Find its total surface area. 1) 225 cm2 2) 900 cm2 3) 1125 cm2 4) 1350 cm2
Total surface area of a cube = 6(side)2 = 6(15)2 = 1350 cm2 Hence, option 4. Q2) Find the curved surface area of a right circular cylinder of base radius 14 cm and height 8 cm. 1) 352 cm2 2) 176 cm2 3) 704 cm2 4) 1408 cm2
Curved Surface Area of a right circular Cylinder of base radius 'r' and height 'h' is 2πrh Curved Surface Area = 2×(22/7)×14×8 = 704 cm2 Hence, option 3. Q3) Find the radius of the base of the right circular cylinder whose height is 9 cm and volume is 1089π cm3 1) 11 cm 2) 10 cm 3) 13 cm 4) 9 cm
Volume of a right circular cylinder of base radius 'r' and height 'h' is πr2h ATQ, πr2(9) = 1089π r2 = 121 r = 11 cm Hence, option 1. Q4) A hollow cylindrical metallic pipe of length 20 cm and external diameter 8 cm is 1 cm thick. If the metal weighs 9 g/cm3, then what is the weight of the pipe. 1) 369 gm 2) 3690 gm 3) 36.9 gm 4) 3.69 gm
External radius = 4cm Internal radius = 3 cm Volume of the metal = (22/7)×(42 - 32)×20 = 440 cm3 Weight of the metal = 440×9 = 3690gm Hence, option 2. Q5) If radius of a sphere is increased by 10%, find the percentage change in it’s Volume? 1) 30% 2) 10% 3) 133.1% 4) 33.1%
Volume of a Sphere = (4/3)πr3 As, (4/3)π is a constant hence Volume of a Sphere varies directly as the cube of radius. So, Let us suppose the initial radius be 1 unit. Hence, Initial Volume = 13 = 1 unit As, radius of a Sphere is increased by 10% ∴ New radius = 1.1 units Hence, Final Volume = (1.1)3 = 1.331  Hence, option 4. |