Help with loops

[freckles]

Here is what I tried most recently (I've been trying a million different things all morning).

grades_list = float(input('Enter Grades:n')

total = 0
for iter in grades_list:
    total += iter
print("Max =", max)
print("Min =", min)
print("Avg =", total/len(grades_list))

The error I receive simply says: invalid syntax

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The issue that I'm having is that the assignment does not go along with our lesson for this week. So I'm trying to teach myself about floating point numbers and how they work with loops.