[RFI] Ethernet RFI

[Ed -K0iL]

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!).

Thanks,
 de ed -K0iL

-----Original Message-----
From:	Jim
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
combination relationship:

          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  /