Bookkeeping: Returning Explorer Answer

Explorer Robert Peary

From last week: “the North Pole is not the only starting point that satisfies the given conditions of South, East, North, Bear. Can you think of any other spot on the planet from which you can walk a mile South, a mile East, a mile North and find yourself back at your original location? “

Answer: I think people “got” this one, or at least the gist of it, based on Facebook responses. YES, indeed there is not just ONE point where this can occur, but an INFINITE AMOUNT OF THEM. You could start from any point on a circle drawn around the South Pole at a distance slightly more than 1 + 1/2 Π miles (about 1.16 miles) from the Pole — the distance is “slightly more” to take into account the curvature of the Earth. After walking a mile South, your next walk of one mile East will take you on a complete circle around the Pole, and the walk one mile North from that point would return you to your starting point. Therefore your starting point could be any one of the infinite number of points on the circle with a radius of about 1.16 miles from the South Pole. But that ain’t all! You could also start at points closer to the Pole, so the walk East would carry you just twice around the Pole, or three times, etc… so clearly there’s more than one answer to this one!


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