Probability

Jun 2019
4
0
Melbourne
If a man has 15 balls in his left pocket and 12 balls in his right pocket and repeatedly grabs either box at random to take a ball out, what is the probability that he gets to a point where he has 10 balls in each pocket?
 

mathman

Forum Staff
May 2007
6,913
762
Assuming each pocket equally likely to be chosen, the question becomes: after choosing 7 balls, what is the probability that he has chosen 5 balls from the left and 2 balls from the right. The answer is the binomial term $\frac{1}{2^7}\binom{7}{5}=0.1640625$.