$grades{$student} .= $grade . " ";
##</code><code>##

#!/usr/bin/perl -w

use strict;

my %grades;

while (<DAT>) {
     chomp;
     my($student,$grade) = split (" ",$_);
     #$grades{$student} .= $grade . " ";
     $grades{$student} = $grade;

}

for (sort keys %grades) {
    my $scores = 0;
    my $total  = 0;
    my @grades = split(" ", $grades{$_});
    for (@grades) {
       $total += $_;
       $scores++;
    }
    my $average = $total / $scores;
    print "$_: $grades{$_}\tAverage: $average\n";
}

__END__
lee  99
lee  100
kim  90
kim  90
kim  95
kim  100
kim  50
lee  75


:!perl -c ./././perl.score
Name "main::DAT" used only once: possible typo at ./././perl.score line 7.
./././perl.score syntax OK