I’m having issues with 16.Exam Statistics -> 7. The Variance.

My code gives the following error:

Traceback (most recent call last):

File “python”, line 26, in

File “python”, line 23, in grades_variance

TypeError: unsupported operand type(s) for /: ‘float’ and ‘list’

```
grades = [100, 100, 90, 40, 80, 100, 85, 70, 90, 65, 90, 85, 50.5]
def print_grades(grades_input):
for grade in grades_input:
print grade
def grades_sum(scores):
total = 0
for score in scores:
total += score
return total
def grades_average(grades_input):
sum_of_grades = grades_sum(grades_input)
average = sum_of_grades / float(len(grades_input))
return average
def grades_variance(scores):
average = grades_average(scores)
variance = 0
for score in scores:
variance += (average - score) ** 2
total_variance = variance / scores
return total_variance
print grades_variance(grades)
```

I don’t understand why it’s not working. Could someone explain it to me so I can fix my code?