Let me add a few comments and suggestions:

• I would declare all variables with my, otherwise you might run into problems later - apart from the fact that it won't run under use strict.
• You were looking for a map solution, here you go:

  #!/usr/bin/perl
  use strict;
  use warnings;
   
  # always check if open fails
  open(DB, '<test.data') or die "Couldn't open file: $!";
  my @numbers = map {
        my ($prod, $num, $dom) = (split /:/)[36,38,40];
        (unpack("A4",$dom) eq 'ATM' && $prod eq 'In Production')?$num:()
    } <DB>;
  close DB;
   
  my $sum;
  $sum += $_ foreach (@numbers);
   
  printf "The average is %.2f.", @numbers ? ($sum/@numbers) : 0;
  [download]

  I'm not saying that this is a better solution, I'd go - for the sake of readability/maintainability - for something straight forward like your first version.
• Instead of the eval you can use a loop like I did or have a look at List::Utils.

-- Hofmator

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