A large grain silo is to be constructed in the shape of a circular cylinder with a hemisphere attached to the?

Well I can't see your figure. You need to have the radius of the hemisphere top that you speak of in order to get a real number answer. The question does not give the final capacity, but I get the idea. Anyway the volume of the cylinder is (pi) r*2 (h of cyl). The volume of the hemisphere is 1/2 a sphere or (2/3)pi(r*3). Add the two volumes together to get a total volume. So the height of the silo = (vol of the cyl)/(pi X r*2).
Since you don't have all the numbers I can only solve the equations which will give you the numbers once you find the total capacity and radius of the hemisphere. Good luck