Multiple choice

Savitri had to make a model of a cylindrical kaleidoscope for her science project. She wanted to use chart paper to make the curved surface of the kaleidoscope. What would be the area of chart paper required by her, if she wanted to make a kaleidoscope of length $25\space cm$ with a $3.5\space cm$ radius? You may take $\left (\pi = \dfrac{22}{7}\right )$

  1. $540\space cm^2$
  2. $520\space cm^2$
  3. $550\space cm^2$
  4. $560\space cm^2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The area of the curved surface of a cylinder is given by 2 * pi * r * h. Substituting the values: 2 * (22/7) * 3.5 * 25 = 2 * 22 * 0.5 * 25 = 550 cm^2.

AI explanation

The area of chart paper needed to cover the curved surface is found using the curved surface area formula for a cylinder, which is 2 * pi * r * h. Substituting the given radius of 3.5 cm and length (height) of 25 cm gives the expression 2 * (22/7) * 3.5 * 25. When you multiply 3.5 by 2, you get 7, which cancels out the denominator of 7. Multiplying the remaining numbers, 22 and 25, gives a final area of 550 square centimeters.

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