Final answer:
The American likely counted to three hundred as a timing mechanism, estimating that it would take five minutes, roughly the time for such a count, for the cobra to emerge, showing practical reasoning.
Step-by-step explanation:
We may infer that the American decided to count to three hundred because he realized it might take five minutes for the cobra to come out. This inference can be made based on the context within a narrative or a story, where timing and anticipation are crucial elements of suspense or a character's decision-making process. The American may have used the count as a timing mechanism, perhaps knowing or guessing that five minutes -- about the time it would take to count to three hundred -- could be necessary for the cobra to emerge, which highlights his practical reasoning rather than a desire to create an amusing party game or to test the guests' control.