[RFI] Ethernet RFI
eedwards at tconl.com
Sun Jan 23 19:59:23 EST 2005
That's what I get for "shooting from the hip" and not looking it up (my EIT
reference book is at work). I stand corrected. (that's why I skipped that
section on the FE exam).
And I saw my mistake in the "64" number, but of course after I hit send.
It should've been only 8 (the number of wires--duh!).
de ed -K0iL
Sent: Sunday, 23 January, 2005 2:32 PM
To: 'RFI Reflector'
Subject: Re: [RFI] Ethernet RFI
Using fomulas from the theory of 'Permutations and
Combinations' the following equation determines the
number of unique groupings (irrespective of the order
or different permutations such as 1, 2 and 2, 1) or
n_C_r = n! / (n-r)! * r!
Therefore given 8 wires and choosing 2 we have:
8_C_2 = 8! / (8 - 2)! * 2!
8_C_2 = 8! / 6! * 2!
8_C_2 = 40320 / 720 * 2
8_C_2 = 28 unique combinations if my math is correct!
Jim / WB5WPA /
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