Math Brain Teasers · Billy-B
Math Brain Teaser #14
From Billy-B's legendary 1001 Puzzle Collection — preserved on Puzz.com since 1998.
Puzzle #14
In a perfectly circular arena, I walk from the edge directly to the center. I then turn directly to my left, & walk in a straight line to the edge of the arena. I then turn to the right & follow along the edge for a total of 500 meters until I arrive at the point that I started from. What is the circumference of the inner edge of the arena?
Reveal Answer
666 2/3 meters — Draw a diagram of the route I took, and then think of it in terms of a pie chart. I walked exactly 3/4 of the way around the arena, so simply multiply the 500 meters I walked by 4/3 to get the answer.
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