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The total surface area of a hollow cylinder which is open from both sides is 4620 sq cm, area of base ring is 115.5 sq cm and height is 7 cm. Find the thickness of cylinder.
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Answer 1

Answer

Let the inner and outer radii of hollow cylinder be r cm and R cm respectively. Then,

2πh+2πRh+2πR

2

−2πr

2

=4620 …….(i)

and, πR

2

−πr

2

=115.5 …….(ii)

⇒2πh(r+R)+2(πR

2

−πr

2

)=4620 and, πR

2

−πr

2

=115.5

⇒2πh(r+R)+2×115.5=4620 and π(R

2

−r

2

)=115.5

⇒2π×7(r+R)=4389 and π(R+r)(R−r)=115.5

⇒π(R+r)=313.5 and π(R+r)(R−r)=115.5

⇒

π(R+r)

π(R+r)(R−r)

=

313.5

115.5

⇒R−r=

19

_

7 cm.

I think it is answer