Sam is training for a triathlon, a timed race that combines swimming, biking, and running. Consider the following sentence: In order to swim for an hour, Sam must take time away from work, where he earns $10 per hour. This is in addition to paying a $5 entrance fee for the pool. Which basic principle of individual choice do these statements best illustrate? The cost of something is what you give up to get it. Markets are usually a good way to organize economic activity. People usually exploit opportunities to make themselves better off. Trade can make everyone better off.

To partake in triathlon, Sam is forgoing the amount he would have earned if he went to work instead. This is known as the opportunity cost or implicit cost

Opportunity cost is the cost of the next best option forgone when one alternative is chosen over other alternatives.

Sam has to pay $5 to partake in the triathlon. This amount is known as explicit cost. Explicit cost is the cost incurred in carrying out an activity.

Sam's accounting cost is $5

Sam's economic cost is $5 + $10 = $15

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