It's Okey to be Average

the error message is "Oops, try again. average([3, 0]) 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['homework']) + sum(numbers['quizzes']) + sum(numbers['tests'])
total = float(total)
av = total/(len(numbers['homework']) + len(numbers['quizzes']) + len(numbers['tests']))
return av
```