Multiple choice

The areas of two concentric circles are 962.5 $cm^2$ and 1386 $cm^2$ respectively. Find the width of the ring.

  1. 3.5 cm

  2. 2.5 cm

  3. 1.5 cm

  4. 4.5 cm
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A Correct answer
Explanation

Area1 = pi * R^2 = 1386, R^2 = 1386 * 7 / 22 = 441, R = 21. Area2 = pi * r^2 = 962.5, r^2 = 962.5 * 7 / 22 = 306.25, r = 17.5. Width = R - r = 21 - 17.5 = 3.5.

AI explanation

Using the area formula, the radius of the smaller circle is the square root of 962.5 times 7 divided by 22, which equals 17.5 cm. The radius of the larger circle is the square root of 1386 times 7 divided by 22, which equals 21 cm. The width of the ring is the difference between the radii, 21 minus 17.5, which gives 3.5 cm.

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