Grade   	Midterm1 + Midterm2
A+        >=181
A         >=158
A-        >=145
B+        >=132
B         >=118
B-        >=109
C+        >=101
C         >=91
C-        >=82
D+        >=78
D         >=63
D-        >=40

Target percentages before extra credit:
A+        5.25%
A         18.64%
A         11.11%
B         13.26%
B         17.66%
B-        6.72%
C+        6.41%
C         9.95%
C-        3.49%
D+        1.15%
D         3.46%
D-        0.92%
F         1.98%