goptions reset=all;
goptions horigin=1 in vorigin=1;
data a;  s=sqrt(684);
  do rep = 1 to 20;
  Y=0; t=0; output;
  do t = 1 to 100;
    Y = .9*Y + 900+ S*normal(1827655);
  output; end; end;
proc gplot;
   plot Y*t=rep/vref=9100; * where t>30;
symbol1 v=none i=join r=20 width=3;

* Any statement beginning with * is a comment in SAS
The comment extends to the next semicolon. We are
still in a comment.  I have commented out, so to speak, the
where statement above.  The statements below are simply
a trick to write the program statements on the top of
the graph.  Now here is the end of this comment - >  ;

title "Homework Problem";
title2 j=left "data a;  s=sqrt(684);";
title3 j=left "  do rep = 1 to 20;";
title4 j=left "  Y=0; t=0; output;";
title5 j=left "  do t = 1 to 100;";
title6 j=left "    Y = .9*Y + 900+ S*normal(1827655); ";
title7 j=left "  output; end; end; ";
title8 j=left "proc gplot; plot Y*t=rep; ";
title9 j=left "symbol1 v=none i=join r=20;";
run;