Example Problem
The shipping company Bonjour operates a direct sailing route between New York and the French city Le Havre, with one departure each day in both directions. Specifically, every day at noon in New York, a ship sails to Le Havre, and simultaneously in Le Havre, a ship sails to New York. The crossing takes exactly seven days and seven nights in either direction.
The question is: If you leave New York on a Bonjour ship today, how many other Bonjour ships will you pass at sea before you arrive in Le Havre?* You should count only the company’s ships, and only the ones met at sea (meaning not in the harbor).
Instead, they mentally “zoom out” and examine the larger situation, asking questions like, What’s missing from the current problem statement? Are there elements we’re not considering? Is there anything outside the frame that we are not currently paying attention to?
Our trip takes seven days and nights, so we can figure out that a total of eight ships leaves Le Havre in that period. (One way to check this is to list the weekdays—you’ll see a drawing of that on the next page.)
We must meet all of those ships at sea, except for the 8th and final ship. That one launches just as we arrive in the harbor, so we don’t count it, for a final answer of seven ships.
The calculation is correct, but it is also incomplete: we’ve missed the ships that sailed before our departure and are already at sea when we leave New York.