Thank you very much Ikegami.

One last thing, if I want to create 3 sets of 5 integers each from the integer range 1 to 15 then which one is better from randomness angle:

1. I shuffle the previously "shuffled" list in each iteration, or
2. I shuffle the "original" list in each iteration.

Here is the code:

Method 1:
my @array=(1..15);
my @shufflednumbers=();

foreach my $i (1..3) {
	@shufflednumbers = shuffle (@array);
	print "@shufflednumbers[0..4]";
	@shufflednumbers=();
}

Method 2:
my @array=(1..15);
my @temp=@array;
my @shufflednumbers=();

foreach my $i (1..3) {
	@shufflednumbers = shuffle (@temp);
	print "@shufflednumbers[0..4]";
	@temp=@shufflednumbers;
	@shufflednumbers=();
}