Answer: The surface area of a cylindrical ring is 950.4 square in.
Step-by-step explanation:
We know that the surface area of an open cylinder is given by :-
, where <em>r</em>= radius and <em>h</em>= height
As per given , diameter of cylindrical ring = 6.3 in
then , 
h= 48 in
Now , the surface area of the cylindrical ring = 

Hence, the surface area of a cylindrical ring is 950.4 square in.