Hi, I wrote my code just like this and it returns me "get_class_average([alice]) resulted in an error: 'float' object is not callable"

I have no idea of what's going on

```
def average(numbers):
return float(sum(numbers)) / len(numbers)
def get_average(student):
homework = float(sum(student['homework'])) / len(student['homework'])
quizzes = float(sum(student['quizzes'])) / len(student['quizzes'])
tests = float(sum(student['tests'])) / len(student['tests'])
return 0.1 * homework + 0.3 * quizzes + 0.6 * tests
def get_letter_grade(score):
if score >= 90:
return 'A'
elif score >= 80:
return 'B'
elif score >= 70:
return 'C'
elif score >= 60:
return 'D'
else:
return 'F'
def get_class_average(students):
results = []
for student in students:
average = get_average(student)
results.append(average)
return average(results)
```