A student receives the following grades, with an A worth 4 points, a B worth 3 points, a C worth 2 points, and a D worth 1 point. What is the student's weighted mean grade point score?
B in 2 four-credit classes
D in 1 three-credit class
A in 1 three-credit class
C in 1 four-credit class
Mean grade point score is ___