I'll paraphrase from Hovind's class.
Imagine a candle in a room. Your a scientist, so you want to know how long the candle has been burning and also how tall or large the candle was. So the empirical evidence suggests that the candle is x number of inches and the rate of burning has been x number of centimeters per one hour of observation. How many assumptions would you have to make to come up with a hypothesis of how tall the candle was and when it was lit?
There's one other piece of evidence that you don't mention, but that would be pretty obvious if you were looking at the candle. Can you work out what it is? With that evidence you have all the information you need to make a pretty good estimate of how tall the candle originally was.
'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang