Hey,

first, I did not test the code, second I know this can be accomplished much shorter. Actually, I'm thinking about a oneliner.

Nevertheless, you are a newby and I suggest this code since it is much more readable.

#!/usr/bin/perl
        
my %data;
opendir( DIR, "input/*" );
while( my $file = readdir( DIR ))
{
    open( FILE, $file );
    while ($line = <FILE>)
    {
        chomp( $line );
        $data { $file } -> { sum } += $line;
        $data { $file } -> { count } ++;
    }
    close( FILE );
}
closedir( DIR );                        
    
open( FILE, ">", "result.txt" );
foreach my $file (sort keys %data)
{
    printf FILE "%1.2f\n", $data { $file } -> { sum } / $data { $file 
+} -> { count };
}                               
close( FILE );
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