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Home Aptitude Volume and Surface Area Comments

  • Question
  • If the height, curved surface area and the volume of a cone are h, c and V respectively, then 3?Vh 3 - c 2 + 9V 2 will be equal to?


  • Options
  • A. 0
  • B. 1
  • C. chV
  • D. V2h

  • Correct Answer


  • Explanation

    Let h be the height,
    Volume of the cone = V
    and curved surface area of the cone = c
    ? 1/3 ?r2h = V, ?rl = c
    i.e., ?r?r2 + h2 = c
    ?2r2(r2 + h2) = c2
    Consider 3?Vh3 - c2h2 + 9V2
    = 3? x 1/3?r2h x h3 - ?2r2(r2 + h2)h + 9 x 1/9 x ?2r4 h2
    = ?2r2h4 - ?2r4h2 - ?2r2h4 + ?2r4 = 0


  • Volume and Surface Area problems


    Search Results


    • 1. 
      A cylindrical box of radius 5 cm contains 10 solid spherical balls, each of radius 5 cm. If the top most ball touches the upper cover of the box, then volume of the empty space in the box is?

    • Options
    • A. 2500/3 ? cm3
    • B. 50000 ? cm3
    • C. 2500 ? cm3
    • D. 5000/3 ? cm3
    • Discuss
    • 2. 
      A cone has height which is half of 16.8 cm, while diameter of its base is 4.2 cm. It is melted and recast into a sphere. Find the surface area of the sphere.?

    • Options
    • A. 55.44 sq cm
    • B. 60 sq cm
    • C. 65.58 sq cm
    • D. 59 sq cm
    • Discuss
    • 3. 
      A right circular metal cone (solid) is 8 cm high and the radius is 2 cm. It is metaled and recast into a sphere. What is the radius of the sphere?

    • Options
    • A. 2 cm
    • B. 3 cm
    • C. 4 cm
    • D. 5 cm
    • Discuss
    • 4. 
      A hospital room is to accommodate 56 patients. It should be done in such a way that every patient gets 2.2 m 2 of floor and 8.8 3 of space. If the length of the room is 14 m, then breadth and height of the room are respectively?

    • Options
    • A. 8.8 m, 4 m
    • B. 8.4 m, 4.2 m
    • C. 8 m, 4 m
    • D. 7.8 m, 4.2 m
    • Discuss
    • 5. 
      Water flows into a tank 100 m x 150 m x 2 m through a rectangular pipe 1.5 m x 1.25 m at a speed of 20 km/h. In what time, will the water rise by 2 m?

    • Options
    • A. 96 min
    • B. 50 min
    • C. 48 min
    • D. 75 min
    • Discuss
    • 6. 
      Three cubes with sides in the ration 3 : 4 : 5 are melted to form a single cube whose diagonal is 12? 3 cm. The sides of the cubes are?

    • Options
    • A. 6 cm, 8 cm , 10 cm
    • B. 3 cm, 4 cm , 5 cm
    • C. 9 cm, 12 cm , 15 cm
    • D. None of these
    • Discuss
    • 7. 
      If 1 cubic cm of cast iron weights 21 gm, then the weight of a cast iron pipe of length 1 m with a bore of 3 cm and in which the thickness of the metal is 1 cm, is?

    • Options
    • A. 21 kg
    • B. 24.2 kg
    • C. 26.4 kg
    • D. 18.6 kg
    • Discuss
    • 8. 
      The curved surface area and the total surface area of a cylinder are in the ratio 1 : 2. If the total surface area of the right cylinder is 616 cm 2, then its volume is?

    • Options
    • A. 1632 cm3
    • B. 1078 cm3
    • C. 1232 cm3
    • D. 1848 cm3
    • Discuss
    • 9. 
      10 circular plates each of thickness 3 cm, each are placed one above the other and a hemisphere of radius 6 cm is placed on the top just to cover the cylindrical solid. What is the volume of the solid so for formed?

    • Options
    • A. 264? cm3
    • B. 252? cm3
    • C. 236? cm3
    • D. None of these
    • Discuss
    • 10. 
      Find out the next term in the series 7, 11, 13, 17, 19, ...

    • Options
    • A. 21
    • B. 23
    • C. 27
    • D. None of these
    • Discuss


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