Multiple choice

The volume of the metal of cylindrical pipe is 748 cm3. The length of the pipe is 14 cm and its external radius is 9 cm. Its thickness is -

  1. 1 cm

  2. 2.3 cm

  3. 3.7 cm

  4. 5.2 cm
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A Correct answer
Explanation

Metal volume = π(R² - r²)h = 748. With R=9, h=14: π(81 - r²)14 = 748 → (81 - r²) = 748/(14π) ≈ 17 → r² ≈ 64 → r ≈ 8. So thickness = R - r = 9 - 8 = 1 cm. Option B (2.3) is too large, C and D are even larger.

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