Score distribution and curve for the second midterm:

Raw score	Letter grade	Number of tests

56-60		A+		18
51-55		A		52
46-50		A-		52
41-45		B+		86
37-40		B		47
32-36		B-		50
27-31		C+		38
22-26		C		26
19-21		C-		11
0-17		D+ or less	17

The precise curving function is

C = 4.5 - (60-R)/14.33

where R is the raw score (from 0-60) and C is the curved score (from 0-4.5).