var careerArr = new Array();
careerArr[0] = "mainPic_Careers_01.jpg";
careerArr[1] = "mainPic_Careers_02.jpg";
careerArr[2] = "mainPic_Careers_03.jpg";
careerArr[3] = "mainPic_Careers_04.jpg";
careerArr[4] = "mainPic_Careers_05.jpg";

var max;
max = careerArr.length;
var careersDisp = careerArr[Math.floor((Math.random() * max))];