7/9 The Variance

I keep getting the same error a lot of people are getting: "Oops, try again.

grades_variance([6, 5, 8, 3, 0, 8]) returned 0.1666666667 instead of the expected: 8.0"

I've looked at a lot of the posts here, and my code is fairly similar. I cannot find where I'm going wrong. What am I missing?

Thanks...

```
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 += ((average - score) ** 2)
return variance / len(scores)
print grades_variance(grades)
```