I can't seem to figure this out. How can I use a for loop to accomplish the following?

Code:

classAverage[0] =
(stuArray[0].grade[0] +
stuArray[1].grade[0] +
stuArray[2].grade[0] +
stuArray[3].grade[0])/4;
classAverage[1] =
(stuArray[0].grade[1] +
stuArray[1].grade[1] +
stuArray[2].grade[1] +
stuArray[3].grade[1])/4;
classAverage[2] =
(stuArray[0].grade[2] +
stuArray[1].grade[2] +
stuArray[2].grade[2] +
stuArray[3].grade[2])/4;
classAverage[3] =
(stuArray[0].average +
stuArray[1].average +
stuArray[2].average +
stuArray[3].average)/4;