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InterviewSolution
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A hoiow metai cylinder having external radius 3 em and height 10 cm has a totasurface area of 3331 cm. Find the thickness of the hollow metallic cylinder5. |
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Answer» Let the outer radius be Rand inner radius be r total surface area = inner surface area + outer surface area + 2 ( area of thickness ) . = 2πrh + 2πRh + 2π(R² -r²)⇒338π = 20πr + 160π + 128π - 2πr²⇒2πr² - 20πr + 50π =0⇒r² -10r + 25 =0⇒r²-5r-5r+25=0⇒r(r-5)-5(r-5)=0⇒(r -5)²=0⇒r =5 cm therefore thickness of the metal in cylinder = R- r = 8- 5 = 3 cm. |
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