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Coin through a hole (Posted on 2006-05-29) Difficulty: 2 of 5
Take a piece of paper and cut out a perfect circle with diameter 1 inch.

What is the diameter of the largest unaltered coin which may be passed through the hole without tearing it?

(Consider the coin to be very thin, and the paper to be very flexible and tear resistant, but not at all stretchy.)

  Submitted by Jer    
Rating: 3.0000 (5 votes)
Solution: (Hide)
If the paper is folded across the center of the hole, the hole becomes a half-circle that can be flattened out by pulling back the opposite sides of the crease. The hole then becoms a slit whose width is nearly half the circumference of the circle.

The answer is a diameter of pi/2 minus the width of the coin which is a little over 1.5 inches.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
answer?WAyne2007-10-02 06:33:05
re(6): My 2 cents worthNicole2006-07-03 12:22:06
SolutionSolutionYosippavar2006-06-20 05:53:43
re: EasyVernon Lewis2006-06-17 22:15:37
SolutionEasyLil mz naughty2006-06-17 21:17:20
re: the REAL answerjeffrey2006-06-09 11:11:27
hmmNick2006-06-05 20:47:31
re: The HypotheticalJordie2006-06-04 22:41:23
the REAL answerJordie2006-06-04 22:35:31
the answerAmanda2006-06-04 05:01:14
re(5): My 2 cents worthRichard2006-05-30 15:37:04
re(4): My 2 cents worthRichard2006-05-30 15:25:47
SolutionsummaryCharlie2006-05-30 11:21:16
re(3): My 2 cents worthbrianjn2006-05-30 03:35:57
My guessLarry2006-05-30 01:08:07
The Hypotheticalbrianjn2006-05-30 00:53:36
re(3): My 2 cents worthSalil2006-05-30 00:43:02
re(2): My 2 cents worthRichard2006-05-29 19:46:06
re: My 2 cents worthSalil2006-05-29 18:35:32
My 2 cents worthRichard2006-05-29 15:21:32
re: my guessCharlie2006-05-29 13:10:19
Solutionmy guessCharlie2006-05-29 12:59:01
SolutionMy GuessSalil2006-05-29 12:47:34
Guessatheron2006-05-29 12:37:56
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