In addition to rhesa's recommendation - Your "%hash" most likely does not look the way you expect it to - There are no usable Keys, and the structure does not make logial sense for what you say you need. Here is what your structure looks like: 
$VAR1 = {
          'ARRAY(0x19333b0)' => [
                                  'baz',
                                  5
                                ],
          'ARRAY(0x350c8)' => [
                                'bar',
                                7
                              ]
        };

[download]
Note that it has converted your Arrayref ["foo",1] into a KEY, which is probably not what you want. In any case, a hash-type structure does not seem to be called for , based on your description. I'd sugges an AoA.
Update: AoA Recommended: 
my @Index_Is_The_Weight=(
   [],  # Zero weight - no items
   ["foo"], # Only one item has weight ONE
   [], # No items in weight 2
   ["bar"], # Three
   ([]) x 5, # Five empty items
   ["quux"]
);

[download]

     "A closed mouth gathers no feet." --Unknown

In reply to Re: Picking a random item through probability by NetWallah
in thread Picking a random item through probability by muba

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