Hepl with Review



What is the deal with this one?
I'm not able to figure out how to fix this.

Traceback (most recent call last):
File "python", line 32, in
File "python", line 30, in grades_std_deviation
TypeError: unsupported operand type(s) for ** or pow(): 'list' and 'int'

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

def grades_std_deviation(variance):
    return variance**0.5

print grades_std_deviation(grades)


did you read the instructions?

Print out the following:

all of the grades
sum of grades
average grade
standard deviation

careful about input you pass into each of the functions.



print grades_std_deviation(grades)

you provide grades as argument, but grades_std_deviation can't handle a list as input

you will need to calculate the grades_variance, which produces a number. Of this number, you can then calculate the grades standard deviation.


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