Finding the area of a column within a pipe

[Anthonyk2013]

I have this question where a concrete column is with in a cast iron pipe. The outside diameter is 200mm and the inside diameter is 150mm and I need to find both areas in meters. The area of the concrete column is 3.14*.15^2/4=.176 Area of pipe 3.14*(D^2-d^2)/4=3.14*(.2^2-.15^2)/4=0.0137m^2 are my calculations right?

 

[Anthonyk2013]

Area of concrete =.0176m^2 and the Area of cast iron pipe=.0137m^2 I think what confused me is I thought the area of the concrete would be a lot more then the area of the pipe