496K views • 28 days ago
In a room 30 feet long, 12 feet wide, and 12 feet high, a spider sits in the middle of one end wall, a foot below the ceiling, and a fly sits in the middle of the opposite end wall, a foot above the floor. The spider can only crawl, so what is the shortest way for it to reach the fly?
Puzzle by Henry Dudeney, first printed in 1903 and collected in his book The Canterbury Puzzles (1907).
CHAPTERS
0:00 A spider, a fly, and a room
0:32 Over the ceiling
0:51 Lay it flat
1:21 Along the back wall
2:03 Ceiling, then back wall
2:39 A fourth way to open the room
3:18 Fold it back
3:36 Why nothing is shorter
4:11 Where the puzzle is from
SOURCES
[1] Wikipedia, The spider and the fly problem https://en.wikipedia.org/wiki/The_spider_and_the_fly_problem
[2] Dudeney (1907), The Canterbury Puzzles and Other Curious Problems, puzzle 75, "The Spider and the Fly" https://www.gutenberg.org/ebooks/27635
[3] Dudeney (1919), The Canterbury Puzzles, 2nd ed., solution to puzzle 75 https://www.gutenberg.org/files/27635/27635-h/27635-h.htm
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