#!/usr/bin/perl -w
                                                                                
use strict;
use warnings;
                                                                                
                                                                                
my %servers = (
    'server1' => 'cluster1',
    'server2' => 'cluster1',
    'server3' => 'cluster2',
    'server4' => 'cluster2'
);
                                                                                
my %values = (
    'server1' => 20.00,
    'server2' => 10.00,
    'server3' =>  5.00,
    'server4' => 15.00,
);
                                                                                
my %cluster_count;
                                                                                
#
# Here is where you fill in values, such that...
#
#     $values{'server1'} = <cpu info for server1>
#     $values{'server2'} = <cpu info for server2>
#     ... etc ...
#
# But, I'm going to cheat and do ...
                                                                                
%values = (
    'server1' => 20.00,
    'server2' => 10.00,
    'server3' =>  5.00,
    'server4' => 15.00,
);
                                                                                
my %results_by_cluster;
                                                                                
#
# Calculate results by cluster, and save cluster counts (this is
# necessary for the calculation of averages).
#
foreach my $srvr (keys (%servers)) {
    my $cluster = $servers{$srvr};
    ++$cluster_count{$cluster};
    $results_by_cluster{$cluster} += $values{$srvr};
}
                                                                                
#
# Display results
#
foreach my $cluster (qw(cluster1 cluster2)) {
    my $avg = $results_by_cluster{$cluster} / $cluster_count{$cluster};
    printf "%20.20s average is:  %f\n", $cluster, $avg;
}