var numImages = 6;
var ranImages = new Array(numImages);
        
ranImages[0] = "03_images/apples_01.jpg";
ranImages[1] = "03_images/apples_02.jpg";
ranImages[2] = "03_images/apples_03.jpg";
ranImages[3] = "03_images/apples_04.jpg";
ranImages[4] = "03_images/apples_05.jpg";
ranImages[5] = "03_images/apples_06.jpg";

function pickRandom(range) {
 if (Math.random)
  return Math.round(Math.random() * (range-1));
 else {
  var now = new Date();
  return (now.getTime() / 1000) % range;
 }
}

var choice = pickRandom(numImages);