perplexus.info :: Probability : Mountain Motif

Mountain Motif (Posted on 2010-04-07)

A five digit positive integer is a mountain number if the first three digits are in strictly ascending order and the last three digits are in strictly descending order. For example, 46872 is a mountain number, but none of 43434, 54456 and 46766 is a mountain number.

Determine the probability that N is a mountain number, given that N is a positive integer chosen at random between 40000 and 99999 inclusively.

See The Solution Submitted by K Sengupta

Rating: 3.5000 (2 votes)

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

Subject	Author	Date
Solution (using Excel)	hoodat	2010-04-20 00:37:30
A mountain RANGE?	ed bottemiller	2010-04-08 17:18:56
Let's generalize- no middle point needed	Ady TZIDON	2010-04-08 14:02:58
re(2): my way	Ady TZIDON	2010-04-08 13:05:31
re: my way	Charlie	2010-04-08 12:10:06
my way	Ady TZIDON	2010-04-08 10:09:52
solution	Charlie	2010-04-07 11:44:17
six of one, half-dozen of another	ed bottemiller	2010-04-07 11:40:37

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