Exercise: Computing the average, exam statistics.

I receive this error message: Oops, try again. grades_average([1, 6, 2, 4]) returned 3 instead of the expected: 3.25

In the console my result turns out to: 80.4230769231 - Which I believe is correct?

Can someone please explain what I need to change? Because I think I'm getting the correct answer, I don't really understand the reason for the error message, thank you!

Here is my code below:

```
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
def grades_sum(scores):
total = 0
for score in scores:
total = total + score
return total
def grades_average(scores):
return grades_sum(scores) /len(scores)
print grades_average(grades) #80.4230769231
```