Thank you very much for your answer, in fact my input read file: 
Thomas 60 10 20 85
Samuel 35 90 80 65
Adam   100 90 85 52

[download]
and I wanna write and save it as Hash using that formula, here`s sample output:(Hash) 
Adam 79.35
Samuel 69
Thomas 45

[download]
I tried to do it like this 
use strict;
use Fcntl ':flock';
my $file = "inputdata.txt";
open(INFILE, $file) or die "File Not Found: $!";
flock(INFILE, LOCK_EX);
my @students;
while (<INFILE>) {
   push @students, [split / /, $_];

my %hash;
my @keys = keys(%hash);
@keys = sort(@keys);
foreach my $key(@keys){
print $hash{$key} = $students[0]*0.2 + $students[1]*0.25 + $students[2
+]*0.25 + $students[3]*0.3, "\n";
}
}
close(INFILE);

[download]

In reply to Create Hash from array structure by kanka

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.