Final answer:
The extra fuel burned per hour with the HI-FLOW switch selected can be calculated by comparing the fuel consumption rate with and without the switch.
Step-by-step explanation:
The extra fuel burned per hour with the HI-FLOW switch selected can be calculated by comparing the fuel consumption rate with and without the switch. Let's assume that the regular fuel consumption rate without the switch is X gallons per hour. If the HI-FLOW switch is selected, the fuel consumption rate would be X + Y gallons per hour, where Y represents the extra fuel burned per hour.
Therefore, the amount of extra fuel burned per hour with the HI-FLOW switch selected is Y gallons.