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A hollow cylindrical tube 20 cm long, is made of iron and its external and internal diameters are 8 cm and 6 cm respectively. The volume of iron used in making the tube is ( π = 22/7)
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- 1760 cu.cm.
- 880 cu.cm.
- 440 cu.cm.
- 220 cu.cm.
- 1760 cu.cm.
Correct Option: C
The volume of iron used = πr1²h1 - πr2²h2 = (r1² - r2²)
| = | × 20(4² - 3²) | |
| 7 |
| = | × 20 × 7 = 440 cu.cm. | |
| 7 |
