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The volume of a right circular cone of h...

The volume of a right circular cone of height 24 cm is `1232 cm^(3)`. Its curved surface area is

A

`1254 cm^(2)`

B

`704 cm^(2)`

C

`550 cm^(2)`

D

`462 cm^(2)`

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The correct Answer is:
To find the curved surface area of the right circular cone given its volume and height, we can follow these steps: ### Step-by-Step Solution: 1. **Identify the Given Information:** - Height (h) of the cone = 24 cm - Volume (V) of the cone = 1232 cm³ 2. **Use the Volume Formula for a Cone:** The formula for the volume of a cone is: \[ V = \frac{1}{3} \pi r^2 h \] Here, \( \pi \) can be approximated as \( \frac{22}{7} \). 3. **Substitute the Known Values into the Formula:** Substitute \( V = 1232 \, \text{cm}^3 \) and \( h = 24 \, \text{cm} \) into the volume formula: \[ 1232 = \frac{1}{3} \times \frac{22}{7} \times r^2 \times 24 \] 4. **Rearranging the Equation to Solve for \( r^2 \):** Multiply both sides by 3 to eliminate the fraction: \[ 1232 \times 3 = \frac{22}{7} \times r^2 \times 24 \] \[ 3696 = \frac{22 \times r^2 \times 24}{7} \] Now, multiply both sides by 7: \[ 3696 \times 7 = 22 \times r^2 \times 24 \] \[ 25872 = 22 \times r^2 \times 24 \] Divide both sides by 24: \[ \frac{25872}{24} = 22 \times r^2 \] \[ 1078 = 22 \times r^2 \] Finally, divide by 22 to find \( r^2 \): \[ r^2 = \frac{1078}{22} = 49 \] 5. **Calculate the Radius \( r \):** Now, take the square root of \( r^2 \): \[ r = \sqrt{49} = 7 \, \text{cm} \] 6. **Calculate the Slant Height \( l \):** Use the Pythagorean theorem to find the slant height \( l \): \[ l = \sqrt{h^2 + r^2} = \sqrt{24^2 + 7^2} = \sqrt{576 + 49} = \sqrt{625} = 25 \, \text{cm} \] 7. **Use the Curved Surface Area Formula:** The formula for the curved surface area (CSA) of a cone is: \[ \text{CSA} = \pi r l \] Substitute \( r = 7 \, \text{cm} \) and \( l = 25 \, \text{cm} \): \[ \text{CSA} = \frac{22}{7} \times 7 \times 25 \] 8. **Calculate the Curved Surface Area:** Simplifying: \[ \text{CSA} = 22 \times 25 = 550 \, \text{cm}^2 \] ### Final Answer: The curved surface area of the cone is \( 550 \, \text{cm}^2 \). ---
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RS AGGARWAL-VOLUME AND SURFACE AREA OF SOLIDS-Multiple Choice Questions (Mcq)
  1. The volume of a cone is 1570 cm^(3) and its height is 15 cm. What is t...

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  2. The height of a cone is 21 cm and its slant height is 28 cm. The volum...

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  3. The volume of a right circular cone of height 24 cm is 1232 cm^(3). It...

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  4. If the volume of two cones be in the ratio 1 : 4 and the ratii of thei...

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  5. If the height of a cone is doubled then its volume is increased by

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  6. The curved surface area of one cone is twice that of the other while t...

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  7. The ratio of the volumes of a right circular cylinder and a right circ...

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  8. A right circular cylinder and a right circular cone have the same radi...

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  9. The radii of the bases of a cylinder and a cone are in the ratio 3 : 4...

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  10. If the height and the radius of a cone are doubled, the volume of the ...

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  11. A solid metallic cylinder of base radius 3 cm and height 5 cm is melte...

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  12. A conical tents is to accommodate 11 person such that each person occu...

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  13. The volume of a sphere of radius 2r is

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  14. The volume of a sphere of radius 10.5 cm is

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  15. The surface area of a sphere of radius 21 cm is

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  16. The surface area of a sphere is 1386 cm^(2). Its volume is

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  17. If the surface area of a sphere is (144 pi)m^(2) then its volume is

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  18. The volume of a sphere is 38808 cm^(3). Its curved surface area is

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  19. If the ratio of the volumes of two spheres is 1 : 8 then the ratio of ...

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  20. A solid metal ball of radius 8 cm is melted and cast into smaller ball...

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