A hollow cylindrical tube made of plastic is 3 cm thick. If the external diameter is 20 cm and length of the tube is 49 cm, find the volume of the plastic.
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Correct answer: D
Explanation
The correct answer is Option 4 i.e. 7854 cm3.
Given:
Thickness of plastic = 3 cm
External diameter = 20 cm
External Radius = 20/2 = 10 cm
Then, Internal radius = 10 - 3 = 7 cm
Height = 49 cm
The volume of the hollow cylinder = π × h(R - r)(R + r)
⇒ 22/7 × 49(10 - 7)(10 + 7)
⇒ 22 × 7(102 - (7)2)
⇒ 22 × 7(100 - 49)
⇒ 22 × 7 × 51 = 7854 cm2