Finding the probability distribution p(r) for nearest-neighbor distance in a gas at STP

[Norman]

Please Help- A problem in statistical mechanics

In a gas at STP, let p(r)dr be the probability that an atom has a nearest neighbor between distances r and r+dr. Find p(r).

I am struggling with this question. For STP I can find the particle density. But where do I go from there? Do I need to think of a volume of space between r+dr and r?
I am very confused.

 

[dextercioby]

What's STP...?And what's the shape of the box...?(I'm assuming the gas to be contained in a finite volume box).

Daniel.

 

[Norman]

In a gas at STP, let p(r)dr be the probability that an atom has a nearest neighbor between distances r and r+dr. Find p(r).

This is exactly how the problem is stated.

STP means "standard pressure and temperature" P=1 atm and T=273.15 K

 

[Norman]

I still have no clue, anyone willing to help please?