Let G = HW1 + HW2 + HW3 + EX1+ EX2 
Range  of G  [0,460]

If   the semester was to end NOW (3/19/2018)

 and   380 <= G <= 460  ---> A
       325 <= G <= 380  ---> B or B+
       230 <= G <= 325  ---> C or C+
         0 <= G <= 229  ---> D or F
 Ranges may overlap.

Mon 19 March, 2018 @ 14:19