#!/usr/bin/perl -w
use strict;

my $desired_mean = 250;
my $desired_deviation = 20;
my $total = 1000;

my @numbers;

gen_numbers(\@numbers, $desired_mean, $desired_deviation, $total);

sub gen_numbers {
   my ($array_ref, $mean, $deviation, $total) = @_;
   my $offset = $deviation * 1.75;
   my $low = $mean - $offset;
   my $high = $mean + $offset;
   for (0 .. $total) {
       my $number;
       while (1) {
            $number = int(rand($high)) + 1;
            last if ($number >= $low && $number <= $high);
       }

       push @{$array_ref} , $number
   }
}

my $sum;
$sum += $_ for @numbers;

my $mean = $sum / $total;

my $scratch;
for (@numbers) {
   $scratch += (($_ - $mean) * ($_ - $mean));
}

my $standard_deviation = sqrt($scratch / ($total - 1));

print "Desired Mean:  $desired_mean\n";
print "Mean:  $mean\n";
print "\n";
print "Desired Standard Deviation:  $desired_deviation\n";
print "Standard Deviation:  $standard_deviation\n";
__END__
Desired Mean:  250
Mean:  250.06707

Desired Standard Deviation:  20
Standard Deviation:  19.9571308028178