Independent trial consisting of rolling a fair die perform. What is the probability of $2$ appear before $3$ or $5$??
Well, different explanation of the same question is available on some sites......But I could not figure out what's been asking for? And is there only one trial of rolling?
We are repeatedly rolling a die until one of $2$, $3$, or $5$ appears. If it is a $2$ we have won. The probability that this is the case is ${1\over3}$, by symmetry.