cost of painting a vessel

Amith2006

1. The problem statement, all variables and given/known data

The inner and outer radii of a hollow steel hemispherical vessel are 2 cm and 3 cm respectively.what is the total cost of painting the vessel all over at the rate of 70 cents per cm² ?



[ b]2. Relevant equations[/b]
Curved surface area of hemisphere=2[pi]*[radius]²

3. The attempt at a solution
total Surface area= 2[pi]*{[inner radius]² + [outer radius]²}
TOTAL cost = 0.7*total Surface area

is it right?

csprof2000

Yes, but you can't forget about the rim, with area PI ( [outer radius]^2 - [inner radius]^2 )

Amith2006

u got a point.i was just falling short of the answer by an iota. Thanks buddy.