5 Edited grammar, since this was on the front page anyway

The following problem has bothered me for a long time.

Let us imagine a point on the real axis. At the beginning, it is located at point $O$. Then it will "walk" on the real axis randomly in the following way. For every step of the "walk", it will choose a real number $\Delta x$ in uniformly from the interval $[-1,1]$ equiprobably, and [-1,1]$, turn right, and move$\Delta x$unit. Once it move to reaches the left side of the point$O$, it will "die" immediately. Our task is find out the probability of the point "live" is alive after$n$steps of "walk"$P_n$. I guess that$P_n=\frac{(2n)!}{4^n (n!)^2}$. But n!)^2}$, but I can't prove that it is correct this or explain why it is true.

4 deleted 87 characters in body; edited tags; edited title

# SomethinglooksimplebuthasbotheredmeforalongtimeinProbabilityTheoremArandomwalkwithuniformlydistributedsteps

Hi! ^-^ I'm a new.

The following problem bothered me for a long time.

Now let

Let us imagine a point on the real axis. At the beginning, it is located at point $O$. Then it will "walk" on the real axis randomly. For every step of the "walk", it will choose a real number $\Delta x$ in interval $[-1,1]$ equiprobably, and turn right and move $\Delta x$ unit. Once it move to the left side of the point $O$, it will "die" immediately.

Our task is find out the probability of the point "live" after $n$ steps of "walk" $P_n$. I guess that $P_n=\frac{(2n)!}{4^n (n!)^2}$. But I can't prove that it is correct or explain why.