1 grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
 2 
 3 def print_grades(grades_input):
 4   for grade in grades_input:
 5     print grade
 6 print_grades(grades)
 7 def grades_sum(scores):
 8   total = 0
 9   for score in scores: 
10     total += score
11   return total
12 print grades_sum(grades)
 
13 def grades_average(grades_input):
14   sum_of_grades = grades_sum(grades_input)
15   average = sum_of_grades / float(len(grades_input))
16   return average
17 print grades_average(grades)
18 def grades_variance(scores):
19   average=grades_average(scores)
20   variance=0
21   for score in scores:
22
 
     variance+=(average-score)**2
23   return variance/float(len(scores))
24 
25 print grades_variance(grades)
26 
27 def grades_std_deviation(variance):
28   return variance**0.5
29 
30 variance=grades_variance(grades)
31 
32 print grades_std_deviation(variance)

python list示例