Relation of pressure with mean-free-path

[fricke]

My textbook says "The lower the gas pressure, the higher the mean-free-path".
But it does not explain why.

Can someone please explain it briefly? Thank you very much.

 

[Dr. Courtney]

The mean free path is the average length a gas molecule travels before bumping into another gas molecule.

Other factors being equal, lower pressure means a molecule will travel further before hitting another molecule.

 

[fricke]

The mean free path is the average length a gas molecule travels before bumping into another gas molecule.

Other factors being equal, lower pressure means a molecule will travel further before hitting another molecule.

But how does it related with the pressure? Why is the mean-free-path high when the pressure is lower? How to explain it in term molecular level?

 

[Bystander]

Better statement: the lower the density, the longer the mean free path.