2015 Royal Kona Tour Information
Tour	Lanai	Villager	Sunset
Price per passenger	$78	$83	$107
Fixed Costs (annual)
boat depreciation	$110,000	$100,000	$100,000
boat maintenance	$42,000	$29,000	$30,000
insurance	$5,400	$5,400	$5,400
share of hotel costs	$21,000	$21,000	$21,000
advertising	$18,000	$18,000	$18,000
Variable Costs (per trip)
fuel	$165	$135	$225
tour guide cost	$175	$100	$160
passenger food	$225	$115	$350
docking fees	$78	$100	-
Number of trips per year	223.0	148.0	210.0
Mean passengers per trip	27.0	26.4	27.6
Annual Profit	$129,849.00	$84,297.60	$291,422.00
Added trip profit	$1,463.00	$1,741.20	$2,218.20
Profit margin added per trip	69%	79%	75%
Return on investment	66%	49%	167%

Q5: As an added complication, the food cost for each trip is being charged so that it is not fixed per trip but will be dependent upon the number of passengers on each trip. In other words, if food for one passenger is x, food for 2 passengers would be 2x and so on. Which this change (and given that the current price and other fixed costs remain the same), what is the minimum mean number of passengers needed to be profitable in terms of having a positive return on investment? Alternatively, is there a tool you could use for determining the number of passengers needed to make the trip profitable? If so, what tool is that?