Question 361937
Convert the weight to volume using the density, {{{rho}}}.
{{{W=rho*V}}}
{{{V=W/rho=8200/2400=41/12}}}{{{m^3}}}
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{{{V=(1/3)*pi*h*(R^2+Rr+r^2)=41/12}}}
{{{(1/3)*pi*0.108*(1.1^2+1.1r+r^2)=41/12}}}
{{{r^2+1.1r+1.21=30.21}}}
{{{r^2+1.1r-30=0}}}

Use the quadratic formula,
{{{r = (-1.1 +- sqrt( 1.1^2-4*1*(-30) ))/(2*1) }}} 
You'll get two answers, one negative, one positive.
Only the positive one makes sense here.
The units for the answer will be meters.