var ar = new Array("<IMG SRC=html/BoyGraduatex225.jpg width=230 height=330 border=0>", 
"<IMG SRC=html/GirlsGraduatesx225.jpg width=225 height=272 border=0>",
"<IMG SRC=html/GraduatePaperGirlx250.jpg width=250 height=332 border=0>");

var num = Math.floor(Math.random() * ar.length);
document.write(ar[num]);