Multiple choice

A hollow cylindrical pipe has an outer radius of 14 cm, an inner radius of 12 cm, and a height of 21 cm. Find its volume (approx).

  1. 2280 cm3

  2. 1280π cm3

  3. 1092 cm3

  4. 3430 cm3
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D Correct answer
Explanation

Volume of a hollow cylinder = pi * h * (R^2 - r^2). Here R=14, r=12, h=21. Volume = pi * 21 * (196 - 144) = pi * 21 * 52 = 1092 * pi. Using pi approx 3.14, 1092 * 3.14 = 3428.88, which is approximately 3430.

AI explanation

Using the volume formula for a hollow cylinder, V = pi * (R^2 - r^2) * h, we substitute the outer radius of 14 cm, inner radius of 12 cm, and height of 21 cm. This gives V = pi * (14^2 - 12^2) * 21 = pi * (196 - 144) * 21 = pi * 52 * 21 = 1092 pi. Since we approximate pi as 22/7, the volume evaluates to 1092 * (22/7) = 156 * 22 = 3432 cm3, which is approximately 3430 cm3.

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