# All entries for Monday 13 June 2005

## June 13, 2005

### Probability Puzzle Time!

This puzzle from the GCHQ recruitment website has completely flummouxed me. I suspect there is some sort of general method to dealing with stuff like this, but I have no idea what it is.

2. Alice and Bob play coin toss: Alice pays Bob £1 for each head and Bob pays Alice £1 for each tail they throw. They continue playing until one player loses (runs out of money). Initially Alice has £6 and Bob has £14.

a. Determine, with proof, the probability that Alice loses.
b. Determine the probability that Alice loses but also has at some time previously been within £1 of winning.

## June 2005

Mo Tu We Th Fr Sa Su
May |  Today  | Jul
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30

## Galleries

• Ok this is odd, I got here via Stumble Upon… It's the first time I've come across a Warwick Blogs … by on this entry
• I've been wondering the same question…what's the secret? I know there's an easier way. I'm just go… by Wanda on this entry
• chinese? by confucian on this entry
• Please… please we're not called global warming "deniers" we prefer to be called global warming "in… by Peter Jungmann on this entry
• Now, to continue, if you need evidence that the 1998 anomaly was not due to solar activity, pick a d… by Zhou on this entry