There are 17 railway stations in a railway track between A and B. The train stops at 4 intermediate stations at random. Then the probability that at least two of these 4 stations are consecutive is

Train is to be stopped at 4 stations out of 17. 
Prob (At least two of the 4 stops are adjacent)
=1– prob ( No two of them are adjacent )
$\begin{array}{l}=1-\left[\frac{\left({ }^{\mathrm{n}-\mathrm{r}+1}{\mathrm{C}}_{\mathrm{r}}\right)}{\left({ }^{\mathrm{n}}{\mathrm{C}}_{\mathrm{r}}\right)}\right]\text{ where }\mathrm{n}=17,\mathrm{r}=14\\ =1-\frac{\left({ }^{14}{\mathrm{C}}_4\right)}{\left({ }^{17}{\mathrm{C}}_4\right)}=1-\left(\frac{14.13.12.11}{17.16.15.14}\right)=1-\frac{143}{340}=\frac{197}{340}\end{array}$