There are 10 stations between A and B. A train is to stop at three of these 10 stations. The probability that no two of these stations are consecutive is

$\mathrm{n}\left(\mathrm{S}\right)=10{\mathrm{C}}_3$

E=no two of these stations are consecutive 

3 stations seperated out of 10 remaining 7 stations on the line between 8 gaps $\Rightarrow$ out 8 gaps 3 are selected $\Rightarrow \mathrm{n}\left(\mathrm{E}\right)=8{\mathrm{C}}_3$

$\mathrm{P}\left(\mathrm{E}\right)=\frac{8{\mathrm{C}}_3}{10{\mathrm{C}}_3}$