hello

i have a problem

```
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)
total= total/ len(numbers)
return total
def get_average(student):
homework = average(student["homework"])
quizzes = average(student["quizzes"])
tests = average(student["tests"])
return (0.10 * homework) + (0.30 * quizzes) + (0.60 * 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"
s = get_letter_grade(get_average(lloyd))
print s
def get_class_average(students):
results=[]
for student in students:
ave = get_average(student)
results.append(ave)
return average(results)
print get_class_average(students[lloyd, alice, tyler])
print get_letter_grade(get_class_average(students))
```

and the err output is

```
Oops, try again.
One of the following is missing or broken when we tried to use it:
alice, lloyd, tyler, students, get_class_average, get_letter_grade
```

any help would be appreciated