Two warriors, identical in most respects, are crossing the stone bridge in Deadwind pass heading from Duskwood towards the Swamp of Sorrows. When they are exactly one-quarter of the way along the bridge, they hear a mighty roar behind them: Deathwing is flying in from the west, heading towards Deadwind pass to destroy the bridge and anything still on it. When spotted, Deathwing is exactly one bridge length away from the bridge's western end and moving east towards them awfully, awfully fast.
Jumping off the bridge is not an option. Falling molten chunks of the bridge would surely kill them as they flailed around in the water...assuming they landed in water and not jagged rocks, that is. The only way to survive is to make it off the bridge in either direction: towards Deathwing, or away.
Warrior A takes the direct, albeit risky, approach and immediately turns and runs straight towards Deathwing. Speed and luck are on his side, because he reaches the end of the bridge, turns to the left and makes it two more yards before Deathwing reaches the bridge, and therefore, escapes with his life. At this point, Deathwing starts breathing fire straight down as he travels over the length of the bridge.
Warrior B took the more obvious, if cowardly, solution and immediately started running towards the far end of the bridge, away from Deathwing. He was able to cover a great portion of the bridge's length, but soon, the flames of Deathwing were right behind him. The very instant the flames were just about to touch him, Warrior B uses Heroic Leap (40 yard range) and makes it exactly to the end of the bridge. There, he has plenty of time to run to the side and get to safety.
Calculate the length of the bridge, to the nearest inch.
-- both warriors are moving at identical speeds. I did not, however, tell you if their speed was improved or penalized by any ongoing effects, so the in-game knowledge of movement speed (7 yards a second, or so) is not necessarily correct.
-- Deathwing's speed is unknown but much, much faster than the warriors.
-- Assume that Deathwing's flame is directly beneath him and has no effective radius (i.e. it's a 2-dimensional wall of firey death)
-- Pretend the entire problem is on a straight line. As long as everyone is on the same path (i.e. rails) it's the same problem anyhow.