The individual would gain by choosing air travel if, and only if, his time were valued at more than $10 per hour.
Step-by-step explanation
Cost of airline ticket = $600 and cost of bus ticket = $150
So, the money saved = $600 - $150 = $450
Now, traveling by plane takes 6 hours compared with 51 hours by bus. So, extra travel time = (51 - 6) hours = 45 hours
Thus,
(Money saved / Extra travel time)
dollar/hour
So, the individual would gain by choosing air travel if, and only if, his time were valued at more than $10 per hour.