In: Statistics and Probability
LEt p be the event of getting a tail.
If the out come T appears b times in a row peter will get all the money john has .The probability of this event is
Suppose if a Head appears in between then john will have b+1 dollars( This one dollar is obtained from the peter for the head obtained) . so to get all the money john has T should happen b+1 times, The probability of this event is probability of getting a head in b+2 tosses of a coin=
Now suppose there are two heads occurred before you get b tails. The john will have b+2 dollars. The two more tails will have to happen to take all the money from john . Total number of tosses required for this event is (b+2 )tails+2 heads. The probability of this event is the probability of getting two heads in b+4 tosses=
Similarly if we proceed we get the probability of n heads in b+n tosses =
There fore the Probability that peter wins all the money from john =