This question is a bit difficult for children. It is called Galton plate. Every decline is a choice. The probability of reaching every position on the nth floor obeys the binomial distribution B(n, 1/2) (the leftmost position is marked as 0, and the rightmost position is marked as n).

In this way, the probability of the corresponding position can be calculated (pay attention to the value of the layer number n and the corresponding position of each point).

The result of the original question is correct!

For this binomial distribution, the most likely times are [(n+ 1) 1/2] (rounded) or [(n+1)1/2] = [(n+1)/kloc. When n is an even number, the probability of the middle position is the largest, and so are the probabilities of other symmetrical positions (only for this problem, because the probability is 1/2).