## Problem:

I am a beginner in python programming language. I tried to create a program to calculate my students avarage results so I wrote this code

```
porter = {
"name": "Porter",
"homework": [90.0, 97.0, 75.0, 92.0],
"quizzes": [88.0, 40.0, 94.0],
"tests": [75.0, 90.0]
}
arnub = {
"name": "Arnub",
"homework": [100.0, 92.0, 98.0, 100.0],
"quizzes": [82.0, 83.0, 91.0],
"tests": [89.0, 97.0]
}
opir = {
"name": "Opir",
"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)
avg=total/len(numbers)
return avg
def get_average(student):
homework=average(student["homework"])
quizzes=average(student["quizzes"])
tests=average(student["tests"])
res=0.1*homework+0.3*quizzes+0.6*tests
return res
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"
get_letter_grade(get_average(porter))
def get_class_average(students):
results=[]
for student in students:
results.append=get_average(student)
return average(results)
```

But it shows error message

`"Oops, try again. getclassaverage([porter]) resulted in an error: 'list' object attribute 'append' is read-only"`

Can anyone help me out to solve this problem?