11.Exam Statistics 7.The Variance


#1



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


I am getting this error "Oops, try again.
grades_variance([2, 1, 2, 4, 7, 3, 0]) returned 620.4175824176 instead of the expected: 4.4897959184"


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(grades)
    tot_variance = 0
    variance = 0
    for each in grades:
        variance = variance + (average - each) ** 2
        tot_variance = variance/len(scores)
    return tot_variance 
print grades_variance(grades)


#2

You want to get the average of scores, not grades. But mostly, you're dividing variance by len(scores) every time you iterate through grades. Try taking tot_variance = variance/len(scores) out of the for loop.


#3

Hi I have changed it, but I am still getting this error " Oops, try again.
grades_variance([8, 9, 0, 9, 5, 8, 5, 2]) returned 9603.9765625 instead of the expected: 9.9375"
Please help

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)
    tot_variance = 0
    variance = 0
    for each in grades:
        variance = variance + (average - each) ** 2
    tot_variance = variance/len(scores)
    return tot_variance 
print grades_variance(grades)

#4

Hello, dear aspiring man,
I tried to run your code simply replacing "scores" with "grades" in grades_average, and got the same result, but approved one (I'm still curious, how it's done). Try it!


#5

It's working now. Thank you all for helping me.

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

#6

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