Student Becomes the Teacher/How is Everybody Doing?

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]
}
students = [lloyd, alice, tyler]
#for numbers in students:
    #numbers = ["homework", "quizzes", "tests"]
def average(numbers):
    total = sum(numbers)
    total = float(total)
    return float(total)/len(numbers)
def get_average(students):
    homework =average(students["homework"])
    quizzes = average(students["quizzes"])
    tests = average(students["tests"])
    #return sum(homework *.1, quizzes * .3, tests * .6)
    hweight = homework *.1
    qweight = quizzes * .3
    tweight = tests * .6
    total_sum = hweight + qweight + tweight
    total_sum = float(total_sum)
    return total_sum
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"
    return get_letter_grade(get_average(lloyd))
def get_class_average(students):
    results = []
    for student in students:
        results.append(get_average(student))
    return average(results)
students = [lloyd, alice, tyler]
print get_class_average(students)
print get_letter_grade(students)