Question 171431
the two cylinders are the hollow inside and the outside of the holder


if the thickness is x and the inner radius is 3 then the outer radius is 3+x


volume is πr^2h


[π * (3+x)^2 * 9] - [π * 3^2 * 9] = 200


dividing by 9π __ x^2+6x = 200/(9π) = 7.074 (approx)


completing the square __ x^2+6x+9 = 16.074


taking square root __ x+3 = ±4.009 (approx)


x=1.009 (about one) and x=-7.009