Multiple choice

A metal pipe has an external radius of 4 cm and an internal radius of 3 cm. The volume of the metal of length 10 cm is

  1. $120 cm^2$
  2. $220 cm^2$
  3. $440 cm^2$
  4. $225 cm^2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The volume of a cylindrical pipe is pi * (R^2 - r^2) * h, where R is the external radius and r is the internal radius. Volume = 3.14 * (4^2 - 3^2) * 10 = 3.14 * (16 - 9) * 10 = 3.14 * 7 * 10 = 219.8, which rounds to 220. Note that the units should be cm^3, not cm^2.

AI explanation

Using the volume formula for a hollow cylinder, V = pi * (R^2 - r^2) * h. Substituting the external radius of 4 cm, internal radius of 3 cm, and length of 10 cm gives V = (22/7) * (16 - 9) * 10. This simplifies to (22/7) * 7 * 10, equaling 220 cubic cm.

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