function displayMainImg() {

var randNo = Math.ceil(Math.random()*10);

var imgsrc1 = "intro1.jpg";
var imgsrc2 = "intro3.jpg";
var imgsrc3 = "intro4.jpg";
var imgsrc4 = "intro5.jpg";
var imgsrc5 = "intro6.jpg";

if ((randNo == 1) || (randNo == 2))
{
document.write("<img src='images/index/" + imgsrc1 + "' alt='Intro' style='margin-top:46px;' />");
}

if ((randNo == 3) || (randNo == 4))
{
document.write("<img src='images/index/" + imgsrc2 + "' alt='Intro' style='margin-top:46px;' />");
}

if ((randNo == 5) || (randNo == 6))
{
document.write("<img src='images/index/" + imgsrc3 + "' alt='Intro' style='margin-top:46px;' />");
}

if ((randNo == 7) || (randNo == 8))
{
document.write("<img src='images/index/" + imgsrc4 + "' alt='Intro' style='margin-top:46px;' />");
}

if ((randNo == 9) || (randNo == 10))
{
document.write("<img src='images/index/" + imgsrc5 + "' alt='Intro' style='margin-top:46px;' />");
}

}