Find average of list + 2 inputs - python

Question

I need to find the average of 5 assignments = two inputs. I'm getting a result, but its no correct. Here is what I have:

def main():

  # list of grades
   x = []

   # count of students 
   n = 5

   # fill list with grades from console input
   # using pythonic generator
   x = [int(input('Please enter the grade you got on assignment {}: '.format(i+1))) for i in range(n)]

   midTermGrade = int(input('Please enter the grade you got on you Mid-Term: '))
   finalGrade = int(input('Please enter the grade you got on you Final: '))

   average_assignment_grade = sum(x) + midTermGrade + finalGrade / 7 

   print('Avg grade is ', average_assignment_grade)

main()

As you can see here, the math is wrong, the average suppose to be around 28, not 114

You have to enclose the whole expression of addition with parentheses. Operator precedence and PEMDAS, ie `(sum(x) + midTermGrade + finalGrade) / 7` — Andrew Li, Aug 27 '16 at 00:00

score 2 · Accepted Answer · answered Aug 27 '16 at 00:02

There is a problem with order of operations. You need to change:

average_assignment_grade = sum(x) + midTermGrade + finalGrade / 7

to:

average_assignment_grade = (sum(x) + midTermGrade + finalGrade) / 7

You can read about Python operator precedence here.

score 0 · Answer 2 · answered Aug 27 '16 at 06:26

Karin's answer is correct. Python uses BEDMAS, and that is why you didn't get the expected result.

However you're using Python 3. The statistics module was added in Python 3.4; it has the mean function that will calculate the mean (or "average"):

from statistics import mean

average_assignment_grade = mean(x + [midTermGrade, finalGrade])

The rationale behind this function is that it is not prone to many rounding errors:

>>> a = 100000000000000000.0
>>> sum([a, 3.0, -a) / 3
0.0

but

>>> statistics.mean([a, 3.0, -a])
1.0

Find average of list + 2 inputs - python

2 Answers2