# Sending a Letter 7/9 + sum/grade of all students

#1

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)

# 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
if score >= 90:
return "A"
elif score >= 80:
return "B"
elif score >= 70:
return "C"
elif score >= 60:
return "D"
else:
return "F"

``````

Thank you!

#2

you are going to build a get_class_average function in the next exercise, so its possible

maybe progress first to next exercise?

the problem is that `get_average()` expects a dictionary (alice, lloyd or tyler) as argument on function call

you could make a loop, loop over allstudents, get the average grade of the student and append it to a list

now you have a list with all there grades, which you could average and then optionally convert to a letter grade

i am trying not to spoil too much, this exactly what you will do in the next exercise

#3

Thank you!! You’re my hero!

#4

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