SOLUTION: The density of steel is approximately 7.8 grams per cubic centimeter. An empty steel can with a mass of 76 grams has a radius of 6.1 centimeters and a height of 6.3 centimeters. Es

To estimate the thickness of the steel in this problem, it is ENOUGH to calculate 
the surface area, S, of the can.


Then you will write this equation for the mass 

        S*t*d = 76 grams,    (1)

where t is the thickness (which is small and is assumed uniform over the entire surface),
d is the steel density.


This equation contains only one unknown t, which is under the problem's question
and which you will find from equation (1) as 

        t = .    (2)


So, the only thing to work on is to find the surface area of the can.


The radius is 6.1 cm, the height is h= 6.3 cm,  = 3.14 (approximately), so the surface area is

    S =  +  =  = 475.0192 cm^2,

which you can round to 475 cm^2.


Now the thickness of the material (steel) is, according formula (2)

    t =  = 0.0205 centimeters,


or, in more appropriate units, 0.2 millimeters.   ANSWER