title: is there an algorithm to solve current rating with now one?
body: <p>I have a old rating from the db and a new Rating from the user,
  i tried to search for "rating algorithm" but they save the ratings per user. In my case i don't save the previous ratings. My rating bar is up to max of 5</p>
  
  <p>currently my solution is  oldR + newR/ 2. does this make sense?</p>