Evening All,

Basically I am trying to work out how to calculate the probablity of the number of hands that will be played in a straight forward game of High / Low using cards numbered from 1 to 25. The first card is blindly chosen and then based on probability the choice is made, higher or lower. You only proceed when the guess was correct. That's straight forward enough even for me. But how do I work out the probability for the number of cards to be chosen until the incorrect decision is made. Initially I actually did a trial of 50 plays and came out with an average of 4,37 but how do I actually provide a calculation of the probability.

Any help or advice would be greatly appreciated.

Thanks in advance.

Graham.