Исправленная программа.

pr1.pas

program PR1;
uses crt;
const n=10;
type mas= Array[1..n] of integer;
var
 a:mas;

Procedure menu;
 begin
  writeln('______________________menu');
  writeln('1. vv_mas');
  Writeln('2. viv_mas');
  Writeln('3. a[i]^1/2;(-a[i])^2');
  writeln('4. Srednee arefmeticheskoe');
  Writeln('5.  exit');
  writeln;
  writeln('#?');
 end;


Procedure vvod;
  var i,k:integer;
  begin
   writeln('Vvod massiva__________');
   for i:=1 to n do
    begin
    {a[i]:=-50+random(100);}
    writeln(' Vvedite znachenie #', i, ':');
    readln(k);
    a[i]:=k;
    end;
  writeln('Operation complete. Press any key to continue');
   readkey;
   clrscr;
   menu;
  end;



Procedure vivod;
  var i:integer;
  begin
  writeln;
  writeln('   #','  El');
  writeln;
   for i:=1 to n do
   writeln(i:4,a[i]:4);
   writeln('Operation complete. Press any key to continue');
   readkey;
   clrscr;
   menu;
  end;


Procedure kvkor_kvadr;
  var i: integer;
      j: real;
  begin
  writeln;
  writeln('  #','  El','     Rez');
   for i:=1 to n do begin
    if abs(a[i])=a[i] then j:=sqrt(a[i]) else j:=SQR(a[i]);
    writeln(i:3,a[i]:4,j:8:2);
   end;
   writeln('Operation complete. Press any key to continue');
   readkey;
   clrscr;
   menu;
  end;


Procedure sr_arefm;
  var i,j,s:integer;
      k:real;
  begin
  writeln;
  writeln('  #',' j',' El',' summ');
   k:=0;
   s:=0;
   j:=0;
   for i:=1 to n do begin

   if (abs(a[i])=a[i]) and (i mod 2 = 1) then
    begin
     s:=s+a[i];
     j:=j+1;
     writeln;
     writeln(i:3,j:2,a[i]:3,s:4);
    end;
   end;

   k:=s/j;
   writeln;
   writeln('Srarefm:= ',k:3:2);
   writeln('Operation complete. Press any key to continue');
   readkey;
   clrscr;
   menu;
  end;


var i,j,k:integer;
begin
j:=0;
randomize;

repeat
 clrscr;
 menu;

 if j=0 then
  repeat
   readln(k);
   if (k<>1) and (k<>5) then Writeln('Net znachenii elementov massiva. Zadaite massiv.') else j:=1;
  until (k=1) or (k=5)
 else
  readln(k);

 While (k<1)or(k>5) do
  begin
   Writeln('out of interval');
   readln(k);
  end;

case k of
 1: vvod;
 2: vivod;
 3: kvkor_kvadr;
 4: sr_arefm;
end;

until k=5;
end.