6. The volume of a sphere is 88/21 x (14)³ cm³. The curved surface of this sphere is ?

1. 1. 2424 cm²

   
   
   

   2. 2446 cm²

   
   
   

   3. 2464 cm²

   
   
   

   4. 2484 cm²

   
   
   

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1. View Hint View Answer Discuss in Forum

   ∵ (4/3) x (22/7) x r³ = (88/21) x (14)³
   ⇒ r = 14

   Correct Option: C

   ∵ (4/3) x (22/7) x r³ = (88/21) x (14)³
   ⇒ r = 14
   ∴ Curved surface = 4 x (22/7) x 14 x 14 cm² = 2464 cm²

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7. A hemisphere has 3 cm radius. Calculate its volume. ?

1. 1. 4/3 π cm³
      

   
   
   

   2. 13 π cm³
      

   
   
   

   3. 18π cm³
      

   
   
   

   4. 19/π cm³
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   volume = (2/3)πr³

   Correct Option: C

   volume = (2/3)πr³
   = (2/3) x π x 3³
   = (2/3) x π x 27
   = 18π cm³

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8. A sphere of radius r has the same volume as that of a cone with circular base of radius r. Find the height of the cone. ?

1. 1. 2r

   
   
   

   2. r/3

   
   
   

   3. 4r

   
   
   

   4. (2/3)r

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given that,
   Volume of sphere = Volume of cone
   ⇒ (4/3)πr³ = (1/3)πr²h

   Correct Option: C

   Given that,
   Volume of sphere = Volume of cone
   ⇒ (4/3)πr³ = (1/3)πr²h
   ⇒ 4r = h

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9. Find the total surface area of a pyramid having a slant height of 8 cm and a base which is a square of side 4 cm (in cm²) ?

1. 1. 80

   
   
   

   2. 64

   
   
   

   3. 72

   
   
   

   4. 84

   
   
   

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1. View Hint View Answer Discuss in Forum

   Total surface area of the pyramid
   = [1/2(perimeter of the base) (Slant height) ] + Area of the base
   = 1/2 (4) (4) (8) + 4² = 80 cm²
   

   Correct Option: A

   Total surface area of the pyramid
   = [1/2(perimeter of the base) (Slant height) ] + Area of the base
   = 1/2 (4) (4) (8) + 4² = 80 cm²
   

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10. Half cubic meter of gold sheet is extended by hammering so as to cover an area of hectare. The thickness of the sheet is ?

1. 1. 0.5 cm

   
   
   

   2. 0.05 cm

   
   
   

   3. 0.005 cm

   
   
   

   4. 0.0005 cm

   
   
   

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1. View Hint View Answer Discuss in Forum

   Thickness = Volume / Area

   Correct Option: C

   Thickness = Volume / Area
   = (1/2)/10000 m
   = (1 x 100)/(2 x 10000) cm
   = 0.005 cm

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