# A list of weights; initialized for your problem
my @weights = (8, 1, 1);

# Count the total of all the counts
my $sum;
map { $sum += $_; } @weights;

# Choose a random number, then find a weighted random result
my $target = rand($sum);
for (1..@weights) {
   $target -= $weights[$_];
   last if $target <= 0;
}

print "The number is $_\n";