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 cm2
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 cm2.
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Question : The area of a sector of a circle of radius 8 cm, formed by an arc of length 4.6 cm, is ____.
Option 1: 6.3 cm2
Option 2: 9.2 cm2
Option 3: 18.4 cm2
Option 4: 12.6 cm2
Question : A cylindrical tank of capacity $64\pi$ litres has equal height and radius. What would be the radius of the cylinder? (1 litre = 1000 cm3)
Option 1: 5 cm
Option 2: 40 cm
Option 3: 50 cm
Option 4: 4 cm
Question : What is the total surface area of a solid right circular cylinder of radius 7 cm and height 8 cm?$(\pi=\frac{22}{7})$
Option 1: 560 cm2
Option 2: 660 cm2
Option 3: 850 cm2
Option 4: 760 cm2
Question : A hollow cylindrical tube made of plastic is 3 cm thick. If the external diameter is 20 cm and the length of the tube is 49 cm, find the volume of the plastic.
Option 1: 7238 cm3
Option 2: 7644 cm3
Option 3: 7546 cm3
Option 4: 7854 cm3
Question : The perimeter of a sheet of paper in the shape of a quadrant of the circle is 75 cm. Its area would be $(\pi=\frac{22}{7})$
Option 1: 100 cm2
Option 2: 346.5 cm2
Option 3: 693 cm2
Option 4: 512.25 cm2
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