use strict;
use warnings;

use DateTime;

my $in = DateTime->new(
                       year => 2009,
                       month => 06,
                       day => 22,
                       hour => 8,
                       minute => 30,
                       second => 0,
                      );

my $out = DateTime->new(
                        year => 2009,
                        month => 06,
                        day => 22,
                        hour => 17,
                        minute => 15,
                        second => 0,
                       );

my $duration = $out - $in;

printf("%.2f hour(s)\n",
       $duration->days * 24 +
       $duration->hours +
       $duration->minutes / 60
      );
__END__
8.75 hour(s)