Question 1065225
The amount of metal needed would be the volume needed.  The formula for the volume of a cylinder is:

   {{{ V=pi*r^2h }}}

Where r is the radius of the base
    and h is the height of the cylinder
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You can think of the volume of a cylinder as the area of the base (pi*r^2) times the height (h).   Its also always a good idea to look at units.  in^2 (base area) x in  will give a volume with units of  in^3  which is correct.
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The problem statement gives you the height, and it gives the diameter of the base, just divide the base by 2 to get the radius, then plug in both numbers into the formula.