Question : Deepali made a model of a cylindrical kaleidoscope for her science project. She uses a chart paper to make it. if the length of the kaleidoscope is 25 cm and the radius is 3.5 cm, the area of the paper she used, in the project is: $\left ( \pi=\frac{22}{7} \right )$
Option 1: 1100 cm2
Option 2: 550 cm2
Option 3: 500 cm2
Option 4: 450 cm2
Correct Answer: 550 cm 2
Solution : The area of the paper used to make the cylindrical kaleidoscope $= 2\pi r h$, where \(r\) is the radius of the cylinder and \(h\) is the height of the cylinder. Given: r = 3.5 cm and h = 25 cm Area required = $2 \times \frac{22}{7} \times 3.5 \times 25 = 550 \, \text{cm}^2$ Hence, the correct answer is 550 cm 2 .
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