Multiple choice

Find the curved surface area of a frustum of cone. The slant height is 20 cm, top and bottom radius is 11 and 15 cm respectively. (Use $\pi$ = 3)

  1. 1,860 cm$^2$
  2. 1,760 cm$^2$
  3. 1,660 cm$^2$
  4. 1,560 cm$^2$
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D Correct answer
Explanation

The curved surface area of a frustum is pi * (r1 + r2) * l. Given pi=3, r1=11, r2=15, and l=20, the area is 3 * (11 + 15) * 20 = 3 * 26 * 20 = 1560.

AI explanation

The curved surface area of a frustum is calculated using the formula pi multiplied by the sum of the top and bottom radii and the slant height. Substituting the given values gives 3 multiplied by (11 plus 15) multiplied by 20. This simplifies to 3 multiplied by 26 multiplied by 20, resulting in 1560 square centimeters.

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