k_c said:
Conditional EV = (Unconditional EV - prob(T)*EV(if T is drawn)/(1-prob(T))
Example: hand of 10-2 versus 5, 6 decks full shoe
Unconditional double EV = -.3772
Prob(T) given hand of T-2 v 5 = 95/309
Conditional EV = (-.3772 -95/309*(-2))/(1-95/309) = .3432 = +34.32%
I'm not sure why your figure of 34.32% differs from the figure of 20.5% that I originally quoted. Could you please define the terms in this formula so I can check your work against mine? (Conditional EV, Unconditional EV, prob(T))
From your post it appears to me that maybe you have forgotten to include the fact that the next card cannot be a ten, but it also cannot be an ACE. Perhaps this explains the discrepancy?
A simpler way of figuring this problem and USING the program from that website:
1/8 of the time you will get a deuce for a total of 14; EV = -15.85
1/8 of the time you will get a three for a total of 15; EV = -15.85
1/8 of the time you will get a four for a total of 16; EV = -15.85
1/8 of the time you will get a five for a total of 17; EV = - 4.07
1/8 of the time you will get a six for a total of 18; EV = +19.85
1/8 of the time you will get a seven for a total of 19; EV = +43.69
1/8 of the time you will get an eight for a total of 20; EV = +66.86
1/8 of the time you will get a nine for a total of 21; EV = +89.08
Add these up and divide by 8, and you get an average EV of 20.9%; which is much closer to the 20.5% figure that MY software came up with. (I was using 8 decks rather than 6).
Either way; it's definitely a no-brainer of a double-down if you choose to take it!