Here is the score distribution and curve for midterm 1:

Raw score	Curved grade	Number of tests

69-70		A+			20
63-68		A			85
59-62		A-			65
54-58		B+			63
50-53		B			46
45-49		B-			42
40-44		C+			26
36-39		C			18
31-34		C-			12
26-30		D+			9
22-25		D			8
18-19		D-			4
0-17		F			4

Notes:

1) The curved grade is actually a number from 0 to 4.5.  It is determined by the formula

C = .07R - .61

where C denotes the curved grade and R denotes the raw score.

2) Subsequent exams might be more difficult, as more challenging material is introduced.