$(document).ready(function() {

    function getrandom() {
        var min = 1;
        var max = 11;
        max++;
        var range = max - min;
        var n = Math.floor(Math.random() * range) + min;
        return n;
    }

    var tmp = getrandom();

    $("#home_page_body").css({ 'background-image': 'url("images/' + tmp + '.jpg")' });

});