Multiple choice

A metal of volume 1496 feet3 is used to cast a pipe of length 28 feet. If the internal radius of the pipe is 8 feet, find the outer radius (in feet) of the pipe.

  1. 7

  2. 9

  3. 10

  4. 12

  5. 13
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B Correct answer
Explanation

Volume of pipe = pi * (R^2 - r^2) * L. 1496 = (22/7) * (R^2 - 8^2) * 28. 1496 = 22 * 4 * (R^2 - 64). 1496 = 88 * (R^2 - 64). R^2 - 64 = 1496 / 88 = 17. R^2 = 81. R = 9.

AI explanation

The volume of the pipe is calculated using the formula pi times height times (R squared minus r squared), where R is the outer radius and r is the inner radius. Substituting the known values gives 1496 = 22/7 times 28 times (R squared minus 8 squared). Solving 53.5 = R squared minus 64 results in an outer radius of 9 feet.

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