Circles (Circumference & Area) Quiz - ICSE Class 8 Mathematics
Free practice quiz: Circles (Circumference & Area) (ICSE Class 8 Mathematics). 44 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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A circular park has a radius of 21 meters. What is its circumference?
- 132 meters
- 128 meters
- 138 meters
- 140 meters
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Answer: A. 132 meters
The circumference of a circle is given by the formula C = 2πr. Given r = 21 meters and π ≈ 22/7, C = 2 * (22/7) * 21 = 2 * 22 * 3 = 132 meters.
A circular wire of radius 42 cm is bent into a square. What is the side length of the square?
- 66 cm
- 132 cm
- 84 cm
- 264 cm
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Answer: A. 66 cm
The circumference of the circular wire is equal to the perimeter of the square. Circumference C = 2πr = 2 * (22/7) * 42 = 2 * 22 * 6 = 264 cm. Perimeter of the square = 4 * side. So, 4 * side = 264 cm. Side = 264 / 4 = 66 cm.
A circular wheel of radius 21 cm is rolled along the ground. How many revolutions will it make to cover a distance of 924 meters?
- 700
- 600
- 500
- 800
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Answer: A. 700
First, find the circumference of the wheel. Radius = 21 cm. Circumference C = 2πr = 2 * (22/7) * 21 = 2 * 22 * 3 = 132 cm. The distance to be covered is 924 meters, which is 924 * 100 = 92400 cm. Number of revolutions = Total distance / Circumference = 92400 cm / 132 cm = 700 revolutions.
The circumference of a circle is 132 cm. What is its radius?
- 21 cm
- 42 cm
- 14 cm
- 7 cm
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Answer: A. 21 cm
Circumference C = 2πr. 132 = 2 * (22/7) * r. 132 = (44/7) * r. r = 132 * (7/44) = 3 * 7 = 21 cm.
The difference between the circumference and radius of a circle is 37 cm. Find the radius of the circle.
- 7 cm
- 14 cm
- 21 cm
- 37 cm
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Answer: A. 7 cm
Let the radius be r. Circumference = 2πr. Given: 2πr - r = 37. r(2π - 1) = 37. r(2 * (22/7) - 1) = 37. r(44/7 - 7/7) = 37. r(37/7) = 37. r = 37 * (7/37) = 7 cm.