I am learning Python and I am in Exam Statistic lesson, Standard Deviation
the link to the exercise - https://www.codecademy.com/courses/learn-python/lessons/exam-statistics/exercises/standard-deviation?action=resume_content_item
it is pretty straight forward exerecise, so I wrote down the following code and in the monitor a message says error:
Traceback (most recent call last): File “python”, line 30, in <module> File “python”, line 27, in grades_std_deviation TypeError: unsupported operand type(s) for ** or pow(): ‘list’ and ‘float’
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5] def print_grades(grades_input): for grade in grades_input: print grade def grades_sum(scores): total = 0 for score in scores: total += score return total def grades_average(grades_input): sum_of_grades = grades_sum(grades_input) average = sum_of_grades / float(len(grades_input)) return average def grades_variance(scores): average = grades_average(scores) variance = 0 for score in scores: variance += (average - score)**2 variance = variance / float(len(scores)) return variance def grades_std_deviation(variance): return variance ** 0.5 #line 27 variance = grades_variance(grades) print grades_std_deviation(grades)# line 30
when I checked the solution to this exercise, they did the same thing in def grades_std_deviation.
can you help me understand what I did wrong?