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?
None. It's sufficient to investigate the volume of the room, the construction of the walls, and the difference in air temperature between this room and the adjoining one to determine how much heat the candle has produced, and thus, compared to its current heat of combustion, how long the candle has been burning. (And therefore how tall it originally was.)
Just because you and Kent Hovind aren't sufficiently creative to solve a problem doesn't mean the rest of us are equally dim. It may come as a shock to you but you need to understand that just because you don't know something, doesn't mean nobody else does.