How to plot concentration vs time plot for changing concentrations?

A rod of 10 cm has 20 particles located at the center of the rod. The diffusion begins from the center and the particles go towards left and right. How to plot the concentration of particles at the center of the rod at different times? time=10 minutes. So at the end of every minute, there will be different number of particles at the center. The particles displaces with the following formula: x(t+dt)=x(t)+rD*dt where r is a random number and D=0.1, dt=10 sec (stepsize) It is a one dimensional diffusion. Thank you in advance.

[KSSV]

Read about Scatter

[oshawcole]

Please explain more, I am not able to figure out as I am really new to MATLAB.

[KSSV]

What is r in the above expression? It is a random number conveying what?

[oshawcole]

Random number generated using rand

[Walter Roberson]

If the random number is generated using rand() and is not scaled or shifted, then the particles can only move in the positive direction, contradicting the question requirement that the particles go left and right.