Find the ratio of alpha particles scattering at any angle

[skiboka33]

I'm working on a problem in which I'm asked to find the ratio of alpha particles scattering at any angle (assuming equal numbers of scattering nuclei per unit area)

now I realize that nt = scattering nuclie per unit area. Does this mean that the above restriction sets nt to 1? Wondering because I have the information to find n (atoms/volume) but there is not thickness, t given in the problem. I'm a little new to this material so any help would be appreciated. Thanks.

 

[Meir Achuz]

Since you are asked to find a ratio, nt should cancel in your final answer.