[Tutor] list initialization question

[Tim Condit]

Greetings, 

Why thus?

Why does this fail...

>>> x = []
>>> for i in range(11):
...      x[i] = whrandom.randint(1, 100)
...      print i, x[i]
...  
Traceback (innermost last):
  File "<stdin>", line 2, in ?
IndexError: list assignment index out of range


... but this succeeds? 

>>> x = range(11)
>>> x
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> for i in range(11):
...      x[i] = whrandom.randint(1, 100)
...      print i, x[i]
... 
0 96
1 38
2 20
3 52
4 60
5 7
6 46
7 78
8 5
9 81
10 89


Is it necessary to not only initialize a list, but also to populate it? Or
am I doing something wrong (I hope so..)? If you can add, delete, etc.
items to a list, then why am I getting the error "list assignment index
out of range"? 

Thanks! 
Tim