# 8. Part of a whole

#1

Oops, try again. get_class_average([alice]) resulted in an error: 'NoneType' object is not iterable

Why doesn't it work?

``````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]
}

def average(numbers):
total = sum(numbers)
total = float(total)

def get_average(student):
homework = average(student["homework"])
quizzes = average(student["quizzes"])
tests = average(student["tests"])
return ((0.1 * homework) + (0.3 * quizzes) + (0.6 * tests))

if score >= 90:
return "A"
elif score >= 80:
return "B"
elif score >= 70:
return "C"
elif score >= 60:
return "D"
else:
return "F"
students = [lloyd, alice, tyler]

def get_class_average(students):
results = []
for student in students:
results = results.append(get_average(student))
return average(results)``````

#2

this line:

``results = results.append(get_average(student))``

`append()` will append the items to the list, no need to update the variable as well. so you can just do:

``results.append(get_average(student))``

#3

Works fine now, thanks alot.

#4