How to make my program add the two averages together and calculate one average for the "class"?

Question

I am trying to get my program to add all averages together to generate one big "class" average. The code is only taking the last individual average and dividing that by the number of students in calc_average. Any ideas? Here’s my code:

def calc_average(total):
    return total / student_num
   

def determine_score(grade):
    if 90 <= grade <=100:
        return 'A'
    elif 80 <= grade <= 89:
        return 'B'
    elif 70 <= grade <= 79:
        return 'C'
    elif 60 <= grade <= 69:
        return 'D'
    else:
        return 'F'


student_num=int(input('How many students?'))
for j in range(student_num):
    scores = []
    sum=0
    total=0
    for i in range(0,5):
        score = int(input('Enter Test Scores'))
        print ('Your letter grade is: ', determine_score(score))
        scores.append(score)
        sum=sum+score
    iavg=sum/5
    print('Your average is:', iavg)
total=total+iavg
    
cavg=calc_average(total)
abc_grade=determine_score(cavg)

print('Class average is: ' + str(cavg))
print("The class letter grade would be: " + str(abc_grade))

OUTPUT:
How many students?2

Enter Test Scores80

Your letter grade is: B

Enter Test Scores80

Your letter grade is: B

Enter Test Scores80

Your letter grade is: B

Enter Test Scores80

Your letter grade is: B

Enter Test Scores80

Your letter grade is: B

Your average is: 80.0

Enter Test Scores90

Your letter grade is: A

Enter Test Scores90

Your letter grade is: A

Enter Test Scores90

Your letter grade is: A

Enter Test Scores90

Your letter grade is: A

Enter Test Scores90

Your letter grade is: A

Your average is: 90.0

Class average is: 45.0

The class letter grade would be: F

Asked By: Owen Adams-Mejia

||

Source

Answer 1

Your code for calculating total has two mistakes:

total = 0 happens inside the loop, so on each iteration it gets reset
total += iavg happens outside the loop, so it only happens once

I’d suggest just calculating the average the same way in both cases — build a list, and then sum/divide. Using two different methods of doing the exact same thing makes it easier to confuse yourself.

def determine_grade(score):
    if 90 <= score:
        return 'A'
    if 80 <= score:
        return 'B'
    if 70 <= score:
        return 'C'
    if 60 <= score:
        return 'D'
    return 'F'

student_num=int(input('How many students?'))
averages = []  # average score for each student
for j in range(student_num):
    scores = []  # individual scores for this student
    print(f'Student #{j}:')
    for _ in range(5):
        score = int(input('Enter Test Score: '))
        print('Your letter grade is: ', determine_grade(score))
        scores.append(score)
    avg = sum(scores) / len(scores)
    print('Your average is:', avg)
    averages.append(avg)

class_avg = sum(averages) / len(averages)    
print('Class average is:', class_avg)
print("The class letter grade would be:", determine_grade(class_avg))

Output:

How many students?2
Student #0:
Enter Test Score: 80
Your letter grade is:  B
Enter Test Score: 80
Your letter grade is:  B
Enter Test Score: 80
Your letter grade is:  B
Enter Test Score: 80
Your letter grade is:  B
Enter Test Score: 80
Your letter grade is:  B
Your average is: 80.0
Student #1:
Enter Test Score: 90
Your letter grade is:  A
Enter Test Score: 90
Your letter grade is:  A
Enter Test Score: 90
Your letter grade is:  A
Enter Test Score: 90
Your letter grade is:  A
Enter Test Score: 90
Your letter grade is:  A
Your average is: 90.0
Class average is: 85.0
The class letter grade would be: B

Answered By: Samwise

Answer 2

There are a couple things you can fix.

Total is being set to 0 every time you loop for a new student. Put it above the loop.
You are adding to total after both loops have already gone. Put the addition to total in the loop itself.

These will get your program to run as intended. However, there are still things you can do to make this closer to best practices.

Include a space in your inputs, something like "Input Test Score: "
You’re passing total to an average function, but treating num_students as a global value. While this doesn’t break anything, it doesn’t look right.

Answered By: Lucas

How to make my program add the two averages together and calculate one average for the "class"?

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