If the scores are tied in this weekend's Super Bowl and the game rests on the outcome of a field goal attempt, the chart below will tell you the chances of the goal being made. All you need to know is the distance of the kick:
What this says that if the kick is longer than 50 yards, there's pretty much no chance. The chart was created by Decision Science News (using the R statistical programming language) by tabulating field goal successes for all 10,750 attempts by all NFL teams since 2002. It would be interesting to the stats for just the Ravens and the 49ers; perhaps an R user would use the source data to make the comparison?