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Chessboard Coin (Posted on 2004-10-08) Difficulty: 2 of 5
I've a chessboard of side 80cm.

You've a coin of diameter 2cm, and you throw it on to the chessboard. The center of the coin falls somewhere on the chessboard.

What is the likelihood that the coin is completely within a white square?

  Submitted by SilverKnight    
Rating: 2.8333 (12 votes)
Solution: (Hide)
32%

For the coin to fall within a white square, it (its centre) must fall into a smaller area inside a white square. This smaller area will also be a square with its length 2cm shorter than the 10cm white square. (If the coin falls at the very edge of the white square, its centre will be on the edge of this smaller white square the border of this square will be 1cm away from the border of the larger square) So it must land within this area = 64squared cm.

The area of a white square is 100 square cm = .64 but only every 2nd square is white, so answer = .32

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionSolution (a look at three cases)Dej Mar2008-02-25 23:44:02
answerK Sengupta2007-09-20 16:04:12
re(5): Dumb Questionvenkatesh2005-10-22 06:19:57
re(4): Dumb Questionjohn2005-06-07 17:02:05
re: On edgeajosin2005-03-02 21:04:20
re(2): YupRandyOrton2004-10-18 17:38:16
On edgebob9092004-10-11 06:42:02
re: YupNosher2004-10-10 21:53:34
re: Solution + ExplanationVee-Liem Veefessional2004-10-10 03:42:56
Some ThoughtsNo SubjectVee-Liem Veefessional2004-10-10 03:38:42
no correct answerBen Buergel2004-10-10 01:39:36
re(3): Dumb QuestionCharlie2004-10-08 14:01:40
Questionre(2): Dumb QuestionRichard2004-10-08 13:40:02
re: Dumb QuestionCharlie2004-10-08 12:36:45
QuestionDumb QuestionRichard2004-10-08 12:15:22
YupRandyOrton2004-10-08 10:14:12
oddsrixar2004-10-08 09:52:04
SolutionsolutionCharlie2004-10-08 09:29:35
I agreeRandyOrton2004-10-08 09:15:11
SolutionSolution + Explanationnikki2004-10-08 08:46:23
Some ThoughtsCrude calculations !Syzygy2004-10-08 08:41:48
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