Oops, try again. grades_variance([5, 6, 0, 2, 9, 8, 1, 7, 2]) raised an error: float division by zero

dividing the variance by the score?

```
def grades_variance(scores):
average = grades_average(scores)
variance = 0
for score in scores:
variance += (average - score) ** 2
variance = (variance / score)
return variance
print grades_variance(grades)
```