**Exercise: Sending a Letter 7/9**

The exercise works without problem, **however I would like to get the average of all students** too.

**Why isn’t it possible to see the average of the variable allstudents** ??

The console output is:

B

A

C

Traceback (most recent call last):

File “python”, line 54, in

File “python”, line 32, in get_average

TypeError: list indices must be integers, not str

```
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]
}
# This is the function to define how to calculate an average!
def average(numbers):
total = sum(numbers)
total = float(total)
total = total / len(numbers)
return total
# put [lloyd, alice, tyler] in a variable to make it easier to calculate
allstudents = [lloyd, alice, tyler]
#get the average of the students homework, tests, quizzes
def get_average(students):
homework = average(students["homework"])
quizzes = average(students["quizzes"])
tests = average(students["tests"])
return homework * 0.1 + quizzes * 0.3 + tests * 0.6
# define function to get letter grade on the averages of selected students
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_letter_grade(get_average(lloyd))
print get_letter_grade(get_average(alice))
print get_letter_grade(get_average(tyler))
print get_letter_grade(get_average(allstudents))
```

Thank you!