At an expensive restaurant, a customer makes an unusual request of the chef. She asks that her steak be cooked on a grill until the meat reaches a temperature of 100°C at a depth of 2 mm. The chef knows that the griddle surface temperature is maintained at 250°C, the steak was stored at 0°C, and the steak is 2-cm thick. The customer, an engineer, knows that steak has a heat capacity of 4000 J/kg · K, a density of 1500 kg/m³, and thermal conductivity of 0.6 W/m · K. The chef asks for help. How long should the steak be cooked?