Variance


#1

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 grades:
        variance+=((average-score)**2)
        print variance
        variance=variance/(len(scores))
        return variance
print grades_variance(grades)

why am I getting error ?


#2

from the instructions:

Divide the total variance by the number of scores

the total variance is after the loop, not during, during the loop you are still adding to variance


#3

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