SO in order to calculate that you need to first multiply the number of cups of soup a week by student that the cafeteria need, by the number of students, so if you have S number of student and each needs C amount of cups of soup, the cups of soup total will be CS.
So in order to know how many weeks will X number of cups will last you just divide the number of cups by CS:
We know that diameter=6 ft----------> r=6/2------> r=3 ft h=5 1/3 ft------> (5*3+1)/3-----> 16/3 ft [volume of a cylindrical bales]=pi*r²*h----> pi*3²*16/3---> 150.72 cm³