Please help!

# Add your function below!

def average(numbers):

total = float(sum(numbers))/len(numbers)

return total

def get_average(student):

return 0.1 * average(student["homework"])+\

0.3 * average(student["quizzes"])+ 0.6 * average(student["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"

print get_average(lloyd)

students = ["lloyd", "alice", "tyler"]

def get_class_average(students):

results = []

for student in students:

results.append(get_average(student))

return average(results)

print get_class_average(students)

print get_letter_grade(get_class_average(students))

80.55

Traceback (most recent call last):

File "python", line 45, in

File "python", line 43, in get_class_average

File "python", line 26, in get_average

TypeError: string indices must be integers, not str