As shown, a 280 lb bungee jumper wants to jump from the top of a 420 ft high bridge and be able to just touch the water below. Given that the bungee...

As shown, a 280 lb bungee jumper wants to jump from the top of a 420 ft high bridge and be able to just touch the water below. Given that the bungee cord has a spring constant of 6.19 lb/ft, what should the bungee cord's relaxed length, l, be for this jump?