Question

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 $25cm$ with a $3.5cm$ radius? You may take $(\pi =\frac{22}{7})$

• A. $540c{m}^2$
• B. $520c{m}^2$
• C. $550c{m}^2$
• D. $560c{m}^2$

Answer 1

The correct option is C $550c{m}^2$

Kaleidoscope is of cylindrical shape.

$\therefore$ Area of chart paper required $=$ CSA of cylinder

$=$ $2\pi rh$

$=$ $2\times \frac{22}{7}\times 3.5\times 25$

$=$ $550$ ${cm}^2$