a lot of these answers are just plain wrong.

baking is fundamentally a chemical process, and chemical processes are heavily temperature dependent: almost always thermodynamically, but always kinetically.

and the kinetics are affected by the temperature based on the Arrhenius equation that has a temperature term in an inverted negative exponent.

you could use this equation to figure out the right time difference, if you knew the target temperature and your actual (400dC) temperature.