If the cost of electricity is 8c per kWh, what does it cost to heat 160 L of water for a bath from 9.5°C (the temperature of the water entering the house) to 70°C? I Hint: 1 L of water has a mass of 1 kg. Hint: 1 kWh-1000 J/s × 3600 s.

The temperature in gavin's oven is a sinusoidal function of time. gavin sets his oven so that it has a maximum temperature of 280°f and a minimum temperature of 240°. once the temperature hits 280°, it takes 20 minutes before it is 280° again. gavin's cake needs to be in the oven for 30 minutes at temperatures at or above 270°. he puts the cake into the oven when it is at 260° and rising. how long will gavin need to leave the cake in the oven? (round your answer to the nearest minute.)