By the numbers, the probability of becoming a barister is made up of a few major steps. In mathimatical notation

P(E) where E is the probability of the event

P(E) = Outcomes of E / Total outcomes

or

P(becoming a barister) = Total that make it / Total that try

To make this easy, I'll only take into account three of the steps.

P(E1) = P(getting onto the BVC)

The number of places grabbed from here

BPP - London - 264 places
BPP - Leeds - 48 places
Cardiff Law School - 72 places
College Of Law - birmingham - 96 places
College Of Law - London - 240 places
Inns Of Court School Of Law - 650 places
Manchester Metropolitan University - 108 places
Nottingham Law School 120 places
University of Northumbria at Newcastle - 80 places
University of West England - 120 places

1798 BVC places for 2007 - 2008 session

The other relevent figure here are how many people apply.. I have had to get a google for this one, and the figures banded about on many sites, but I'll cite Target for their obviouse links to the process..

2500 people apply for thise places.. so back to my numbers!

P(E1) = Outcomes of E1 / Total outcomes
or
P(getting on the BVC) = 1798 / 2500
P(getting on the BVC) = 71.92%

Thats a harsh figure, To this point in the budding baristers career is has been quite easy to achive the steps, but now, there is only a 72% chance you'll get a place!

Anyway, back to my maths

P(E1) = 1798 / 2500

P(E2) = P(getting a pupalige)

Given the choice of counting all the pupalages in this years pupaliges handbook, or giving you inferior figures from the year before.. Unfirtunatly the counting approx 500 places didn't quite apeal to me!! and as soon as I get the real numbers, I'll update the figures!!

so, the number of pupillaghes started 06 - 07 was 527 (Source : the sumary in this years pupaliges handbook ).

Again the official figure of how many applications, isn't easy to find. The average of sources i can find, is 2000 applications

P(getting a pupalige) = Outcomes of E2 / Total outcomes
P(getting a pupalige) = 527 / 2000
P(getting a pupalige) = 26.35%

Now thats a shocking figure... for those that don't like maths, for every 100 people that apply, only 26 of them get a place..

Notes:

I'm no math expert, this was for fun!! the figures are good, but there could be some notation not quite right. On that note, I use the "/" to represent divide, and "*" to represent multiply.