var currentImage = 0;
var maxImages = 11;
function setPromotionImage()
{
    currentImage = (Math.random() * 10) % maxImages;
    $("#promotion_image").attr("src", baseUrl + "/img/photos/" + parseInt(currentImage) + ".JPG");
}

 $(document).ready(function(){
    setPromotionImage();
    setInterval(setPromotionImage, 3000);
 });