perplexus.info :: Geometry : Random chord problem

Random chord problem (Posted on 2009-05-11)

Pick two points at random on a circle and draw the chord connecting them.

Pick two more points and connect them with a second chord.

What is the probability that these chords intersect?

Submitted by Jer

Rating: 3.0000 (1 votes)

Solution: (Hide)

1/3
Pick the 4 points and before connecting them label them in order A,B,C,D. The chords will only intersect if A is connected to C.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
re: solution, maybe	Ady TZIDON	2023-11-20 04:35:41
Puzzle Thoughts	K Sengupta	2023-08-03 09:45:32
re(2): solution, maybe (good question)	Jer	2009-05-12 13:47:39
re(3): solution, maybe	Steve Herman	2009-05-12 13:37:17
re(2): solution, maybe	Charlie	2009-05-12 11:10:59
re: solution, maybe	Charlie	2009-05-11 22:56:01
re(2): solution, maybe (good question) (my bad)	Daniel	2009-05-11 21:03:33
Finishing the math (spoiler)	Steve Herman	2009-05-11 20:45:02
re: solution, maybe (good question)	Daniel	2009-05-11 20:09:37
solution, maybe	Stephanie	2009-05-11 19:35:23
re: Is this?	Charlie	2009-05-11 17:27:58
Is this?	pcbouhid	2009-05-11 17:21:38
re: difficulty-one	Charlie	2009-05-11 17:20:48
difficulty-one	ed bottemiller	2009-05-11 16:42:31
re: That can't be right (Hint, Spoiler)	Charlie	2009-05-11 12:55:43
That can't be right (Hint, Spoiler)	Steve Herman	2009-05-11 12:39:41
solution	Daniel	2009-05-11 12:03:38

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