#! perl -slw
use strict;
use Data::Dump qw[ pp ];
use List::Util qw[ shuffle sum ];

use constant TARGET => 100;

sub pick {
    my( $scoresRef, $pickPoint ) = @_;
    my $n = 0;
    ( $n += $scoresRef->[ $_ ] ) > $pickPoint 
       and return $_ 
       for 0 .. $#{ $scoresRef }
}

sub score {
    my( $result ) = @_;
    return TARGET / ( TARGET + abs( TARGET - $result ) ) * 3;
}

my %stats;
for( 1 .. 1e3 ) {
    my @results = shuffle map $_*10, 1 .. 19;
    my @scores = map score( $_ ), @results;
    my $total = sum @scores;
    for ( 1 .. 1000 ) {
        my $picked = pick( \@scores, rand( $total ) );
        ++$stats{ $results[ $picked ] };
    }
}

my $total = sum values %stats;
for my $key ( sort{ $a <=> $b } keys %stats ) {
    printf "%3d : %6d (%.3f%%)\n", $key, $stats{ $key }, $stats{ $key } * 100 / $total;
}

__END__
c:\test>test.pl
 10 :  39702 (3.970%)
 20 :  41626 (4.163%)
 30 :  44526 (4.453%)
 40 :  47013 (4.701%)
 50 :  49309 (4.931%)
 60 :  53178 (5.318%)
 70 :  57689 (5.769%)
 80 :  62036 (6.204%)
 90 :  67798 (6.780%)
100 :  74497 (7.450%)
110 :  67891 (6.789%)
120 :  62295 (6.229%)
130 :  57471 (5.747%)
140 :  53166 (5.317%)
150 :  49932 (4.993%)
160 :  47001 (4.700%)
170 :  43562 (4.356%)
180 :  41775 (4.178%)
190 :  39533 (3.953%)