The error on the console shows:

Traceback (most recent call last):

File "python", line 30, in

NameError: name 'variance' is not defined

The functions above is directly from the previous few exercises, which should be correct.

However what is my mistake in the print part?

```
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:
variance=variance+(average - score) ** 2
results=float (variance) / len(scores)
return results
print grades_variance(grades)
def grades_std_deviation(variance):
return variance ** 0.5
variance=grades_variance(grades)
print grades_std_deviation(variance)
print print_grades(grades)
print grades_sum(grades)
print grades_average(grades)
print grades_variance(grades)
print grades_std_deviation(variance)
```