What is the Cost of Painting a Vessel with Given Dimensions?

[Amith2006]

Homework Statement

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. Homework Equations [/b]
Curved surface area of hemisphere=2[pi]*[radius]²

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]

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

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