A simple heater for a cup of water consists of an insulated resistive coil that plugs directly into a 120 V electrical outlet. The heater is placed into a coffee mug that contains 0.550 kg of water and heats it to boiling (100°C) from room temperature (20°C) in 180 s. If the specific heat of the water is 4200 J/kg·K over this temperature range, what is the resistance of the coil? Ignore any changes in the resistance of the coil due to the increase in temperature.