No clue what is wrong, the error message says:

Traceback (most recent call last):

File "python", line 67, in

TypeError: cannot concatenate 'str' and 'float' objects

```
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) / float(len(numbers))
return total
def get_average(student):
homework = average(student["homework"])* 0.1
quizzes = average(student["quizzes"])* 0.3
tests = average(student["tests"])* 0.6
avrg = homework + quizzes + tests
return avrg
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 "Lloyd: " + get_letter_grade(get_average(lloyd))
print
print "Alice: " + get_letter_grade(get_average(alice))
print
print "Tyler: " + get_letter_grade(get_average(tyler))
students = [lloyd, alice, tyler]
def get_class_average(students):
results=[]
for student in students:
results.append(get_average(student))
return average(results)
print
print
print "Class number average: " + get_class_average(students)
print "Class letter average: " + get_letter_grade(get_class_average(students))
```