Hello,

Could you please guide me to the right direction?

I am kinda lost with a variance function:

```
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
def print_grades(n):
for i in n:
print i
def grades_sum(n):
for i in n:
return sum(n)
def grades_average(n):
return grades_sum(n) / float(len(n))
print grades_average(grades)
def grades_variance(n):
average = grades_average(n)
variance = 0
for i in n:
variance = (average - i) ** 2
return variance / len(n)
print grades_variance(grades)
```