codeacademy variance calculator

grades_variance.py

grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]


def print_grades(grades):
    for grade in grades:
        print grade


def grades_sum(grades):
    total = 0
    for grade in grades:
        total += grade
    return total


def grades_average(grades):
    sum_of_grades = grades_sum(grades)
    average = sum_of_grades / len(grades)
    return average

average = grades_average(grades)


def grades_variance(grades, average):
    variance = 0
    for i in grades:
        diff = average - i
        print "diff is: %r" % diff
        square = diff ** 2
        print "square is: %r" % square
        variance += square
        print "variance is: %r" % variance
    return (sum(variance)) / (len(grades))
    print "sum(variance) / len(grades) is: %r" % (sum(variance) / (len(grades)))

print grades_variance(grades, average)