The error message: Oops, try again. get_class_average([alice]) resulted in an error: list indices must be integers, not str

What's wrong with my code?

```
lloyd = {
"name": "Lloyd",
"homework": [90.0, 97.0, 75.0, 92.0],
"quizzes": [88.0, 40.0, 94.0],
"tests": [75.0, 90.0]
}
alice = {
"name": "Alice",
"homework": [100.0, 92.0, 98.0, 100.0],
"quizzes": [82.0, 83.0, 91.0],
"tests": [89.0, 97.0]
}
tyler = {
"name": "Tyler",
"homework": [0.0, 87.0, 75.0, 22.0],
"quizzes": [0.0, 75.0, 78.0],
"tests": [100.0, 100.0]
}
# Add your function below!
def average(numbers):
total=sum(numbers)
total=float(total)
return total/len(numbers)
def get_average(student):
homework=average(student["homework"])
quizzes=average(student["quizzes"])
tests=average(student["tests"])
homework=homework*0.1
quizzes=quizzes*0.3
tests=tests*0.6
return homework+quizzes+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:
results.append(get_average(student))
return get_average(results)
```