Before vanity plates were a thing, Brigham Young University fans would go to a particular county in Utah and sleep overnight in line to get plates of the form BYU-NNN where the Ns were numbers. On Mon, Sep 23, 2013 at 11:05 AM, meekerdb <meekerdb@verizon.net> wrote:
On 9/23/2013 4:00 AM, Simon Plouffe wrote:
Hello,
I live in france now and they have a plate numbering system that puzzles me a little bit.
Here are some explanations about a new system : http://en.wikipedia.org/wiki/Vehicle_registration_plates_of_France
roughly, the plates are sequenced with letters and digits: in the following way.
AA 123 XX
where letters are a-z except I O and U for various reasons. There are some specific restrictions on some specific 2 letters combination , but we can consider this factor being negligible.
So, they began this numbering scheme in march 2009. Beginnin with AA, for now the letters are at CY,
So to make it simple there are 2 types of plates you can encounter by random.
1) the current numbering system 2) the old system + the foreigns plate that we do not count.
So , for my car the first letters are CG this means there is about 1 chance out of 72 (rejecting the plates of type 2). that I encounter a car with these same letters. And consequently, there is 1 chance in 72 that I encounter CW or BT etc. Since there are 24 letters for each and they covered 3 letters so far then there are 72 combinations.
BUT the problem is the following, this 1 chance out of 72 does not follow statistical distribution at all. , like this morning I encountered 5 vehicles with the prefix CW and I really can't explain why, I calculated that in one day I could see and analyse maybe 100 cars with plate numbers but each day the basic statistics does not add up at all .
Where I used to live in Texas, automobile license plates were obtained at local offices, usually a county government office. Large batches of sequentially numbered plates would be sent to each local office. So all the cars getting plates within some period of time in that area would have the same prefix.
Brent
I am scratching my head and I cannot see why there is a strong statistical bias in the distribution of those 2 letter prefixes.
Can anybody ever encountered such bias.
By the way, this method of analysis was used during WWII , they where doing reverse engineering on the serial numbers found on tanks and planes to know how many the enemy might have, , they eventualy changed to a more cryptic numbering system.
Best regards,
Simon Plouffe _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
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