The Variance


#1



https://www.codecademy.com/courses/python-intermediate-en-7mgOa/2/1?curriculum_id=4f89dab3d788890003000096


grades_variance([1, 8, 9, 2, 9, 1, 1, 1, 4]) returned None instead of the expected: 11.7777777778


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 / float(len(grades))
    return average

def grades_variance(scores):
    average = grades_average(scores)
    variance = 0
    for score in scores:
        variance += (average - score) ** 2
    variance /= len(scores)
print grades_variance(grades)


#2

to return something, use the return keyword, make sure your function returns the correct value


#3

Thanks I forgot to return the variance lol


#4