I get the following error message, any help would be appreciated.
Traceback (most recent call last):
File "python", line 31, in
File "python", line 29, 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): 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) avg = sum_of_grades / float(len(grades)) return avg def grades_variance(grades): average = grades_average(grades) variance = 0 for score in grades: sqd = (average-score)**2 variance += sqd var = variance / float(len(grades)) return var print grades_variance(grades) def grades_std_deviation(variance): return variance**0.5 variance = grades_variance(grades) print grades_std_deviation(variance)