The total (percentage) score was computed by weighting homework 20% (worse hw score was dropped), midterm and final 40% each.
A 95 % total score corresponds to a 4.0, a 72% to a 3.0 and a 60% to a 2.0. Grades were computed according to the formula : (T is your total percentage score)
Final grade= 3+(T-72)/23 if T>=72
Final grade =2+(x-60)12 if T < 72