$(document).ready(function(){
   randomimage();
});

function randomimage() {
   $('body').find('div#brand').each(function() {
      var imgArray = [
         '/images/lifestyle01.jpg',
         '/images/lifestyle02.jpg', 
         '/images/lifestyle03.jpg', 
         '/images/lifestyle04.jpg', 
         '/images/lifestyle05.jpg', 
         '/images/lifestyle07.jpg',  
         '/images/lifestyle08.jpg', 
         '/images/lifestyle09.jpg', 
         '/images/lifestyle10.jpg' ];
      function ranNum(){ return Math.floor(Math.random()*imgArray.length); }
      var ranNum = ranNum();
      var bgimage = imgArray[ranNum]
      $(this).css({'backgroundImage':'url('+bgimage+')'})
   }); //each
} //randomimage