Post
Topic
Board Gambling
Re: Challenge: What's the best way to win 1 BTC with 1 BTC?
by
dooglus
on 19/10/2015, 01:21:02 UTC
Chance of winning = 1 - ((1 - 0.02%) ^ 3430 * (1 - 0.01%)) = 49.649851332%.

Chance of winning = 1 - ((1 - 0.03%) ^ 2287) = 49.651579392%

I notice the word "them" in the quote. Do I get 0.1 btc for beating dooglus' solution? Tongue

My recent post shows strategies that give a 49.6522222% percent chance of winning, so your post (which came after) doesn't beat mine.

Are you able to beat 49.6522222%, or do you think that is a hard limit?

Here's a chart showing your two strategies, and where they fit on the curve of possible martingale strategies. The higher the payout multiplier you play with, the closer you get to the 49.652222% chance:



I wonder if flat-betting would be better?

Like we could divide the 1 BTC into N=10 0.1 bets.
Bet the first 0.1 at 11x. If we win, we're 1 BTC up, so we stop.
Bet the 2nd 0.1 12x. If we win, we're 1 BTC up, so we stop.
Etc.
Bet the Nth at (10+N)x. We're always 1 BTC up if we win.

Turns out it isn't better. What's funny is it is exactly the same.

Here's a Python script that calculates the chance of doubling up using this flat-betting strategy for various N:

Quote
for m in range(0, 6):
    for N in range(10**m, 10**(m+1), 10**m):
        p = 1.0
        for i in range (1, N+1):
            p *= (1 - 0.99 / (N+i))

        print "%6d %.8f" % (N, 1 - p)

And here's its output:

Quote
     1 0.49500000
     2 0.49582500
     3 0.49607333
     4 0.49619171
     5 0.49626081
     6 0.49630606
     7 0.49633797
     8 0.49636168
     9 0.49637999
    10 0.49639455
    20 0.49645915
    30 0.49648035
    40 0.49649088
    50 0.49649718
    60 0.49650137
    70 0.49650436
    80 0.49650660
    90 0.49650834
   100 0.49650973
   200 0.49651599
   300 0.49651807
   400 0.49651911
   500 0.49651973
   600 0.49652015
   700 0.49652044
   800 0.49652067
   900 0.49652084
  1000 0.49652098
  2000 0.49652160
  3000 0.49652181
  4000 0.49652191
  5000 0.49652198
  6000 0.49652202
  7000 0.49652205
  8000 0.49652207
  9000 0.49652209
 10000 0.49652210
 20000 0.49652216
 30000 0.49652218
 40000 0.49652219
 50000 0.49652220
 60000 0.49652220
 70000 0.49652221
 80000 0.49652221
 90000 0.49652221
100000 0.49652221
200000 0.49652222
300000 0.49652222
400000 0.49652222
500000 0.49652222
600000 0.49652222
700000 0.49652222
800000 0.49652222
900000 0.49652222

It converges on 49.6522222% chance of doubling up again!