Volume of a metallic cylindrical pipe is 748 m3. Its internal radius is 8 m and thickness is 1 m. Find the length of the cylinder. (use ) एक धात्विक बेलनाकार पाइप का आयतन 748 मी.3 है। यदि आन्तरिक त्रिज्या 8 मी. है और मोटाई 1 मी. है। बेलन की लम्बाई ज्ञात कीजिए।

For a cylindrical pipe, volume = π(R² - r²)×h where R = outer radius = 8+1 = 9 m, r = inner radius = 8 m, and h = length. Cross-sectional area = π(9² - 8²) = π(81-64) = 17π. Given volume = 748 m³, so h = 748/(17π) = 748/53.41 ≈ 14 m. Option A (16 m) would require different radius values. Option D (12 m) is a common miscalculation error.