Posted by ken on .
a storage bin is shaped like a cylinder with a hemisphere shaped top. the cylinder is 45 inches tall. the volume of the bin is 4131 pi cubic inches. find the radius of the bin.
i think [4(pi)r(cubed)]/3=volume of hemisphere
and h (pi) r squared volume of the cylinder.
so
[4(pi) r (cubed)/3] + [45 (pi) r squared= volume of bin
so
[4 r (cubed)/3] + [45 (pi) r squared=volume
how do i solve for r?
sorry, i'm stuck

algebra 
bobpursley,
the volume of a sphere is 4/3 PI r^3, so a hemisphere would be half of that.
If you have an equation such as this,
a r^3 + b r^2 + c=0
it is a third degree equation. I think I would graph
f(r)= a r^3+b r^2+c and see where it crosses the axis, that is a solution.
There are ways to solve cubic equations, but for this, I would graph it. 
algebra 
ken,
thanks Mr. Pursley,
graphing it now.