Final answer:
The driver concludes that the headlights, which draw 6.67A from the 12-V, 100Ah rated battery, will have enough power to last for approximately 15 hours.
Step-by-step explanation:
The driver is dealing with a problem related to electric circuits and power consumption. First, the power consumption of the headlights needs to be determined by adding the power rating of both headlights, which results in 80W (40W + 40W).
Next, to find out how long the battery will last, the total power (in watts) is converted to amps by dividing the total watts by the voltage (80W / 12V = 6.67A). Since the battery has a capacity of 100Ah, the duration for which the headlights can run is calculated by dividing the battery capacity by the current drawn (100Ah / 6.67A).
This results in approximately 15 hours of run time. Therefore, the driver concludes that the headlights will shine for about 15 hours before the battery is depleted.