Surface and Area

Q 9: Find the Surface area of a cube whose volume is given by: 1000 cm3 A)580 sq. cm B)600 sq. cm C)620 sq. cm D)None of these Answer : Option B Explanation: Let the edge of cube=a cm Then volume of the cube= a3 cu. cm and Surface area =6a2 sq. cm a3=1000 a=10 cm Total S.A=6a2=6(10)2=600 sq. cm Q 10: Find the volume of a cuboid of length 10 cm, breadth 5 cm and height 2 cm. A)120 cm3 B)80 cm3 C)85 cm3 D)100 cm3 Answer : Option D Explanation: Length of the cuboid = 10 cm Breadth of the cuboid = 5 cm Height of the cuboid = 2 cm Therefore, volume of the cuboid = length × breadth × height = (10 × 5 × 2) cm3 = >100 cm3 Q 11: If the volume of a room is 800 m3 and the area of the floor is 100 m2, find the height of the room. A)8m B)7m C)9m D)5m Answer : Option A Explanation: Volume of the room = 800 m3 Area of the floor (l × b) = 100 m2 Therefore, height of the room = (Volume of the room)/(area of the floor) = 800 m3/100 m2 = 8m Q 12: How many cubes of 4cm edge can be cut out of a cube of 64cm edge A)3096 B)4000 C)4096 D)4194 Answer : Option C Explanation: number of cubes=(64 x 64 x 64) / (4 x 4 x 4) = 4096

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