The random walk model employed to explain gas diffusion can be treated as the binomial distribution similar to coin flips with the 50/50 chance that a particle will move in either +x or the -x direction.
a) If ten steps are taken, how much more likely is it that the particle didn't move (Δx=0 after 10 steps) compared to condition where the particle moved ten steps in the +x direction?
b) If ten steps are taken, how much more probable is it that the particle didn't move compared to a condition where the particle ended up 4 steps in the +x direction? Ensure that your steps add up to 10.