18 times
We are given;
We are required to calculate the number of times the kettle can be boiled.
Energy = Voltage × Current × time
Voltage = 12 V
Current = 100 Amperes
Time - 1 hour or 3600 sec
Therefore;
Energy from the battery = 12 V × 100 A × 3600 sec
= 4,320,000 Joules
Energy = Power × time
In this case;
Power is 0.8 kW or 800 watts
Time = 5 mins or 300 seconds
Therefore;
Energy required to boil a kettle
= 800 watts × 300 seconds
= 240,000 Joules
We divide the total amount of energy from the battery by the energy needed to boil one kettle.
Number of times = 4,320,000 Joules ÷ 240,000 Joules
= 18 times
Therefore, the kettle can be boiled 18 times using energy from the battery.