A distance is covered by a cyclist at a certain speed. If a jogger covers half of distance in double time, ratio of speed of jogger to that of cyclist is :

$$\eqalign{ & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{Cyclist}}\,:{\text{Jogger}} \cr & {\text{Ratio of distance}} \to \,\,\,\,\,2\,\,\,\,\,\,\,:\,\,\,\,\,\,\,1 \cr & {\text{Ratio of time}}\,\,\,\,\,\,\,\,\, \to \,\,\,\,\,\,1\,\,\,\,\,\,\,:\,\,\,\,\,\,\,2 \cr & {\text{Ratio of their speed }}\left( {{\text{Jogger}}:{\text{Cyclist}}} \right) \cr} $$
$$\eqalign{ & = \frac{1}{2}:\frac{2}{1} \cr & = 1:4 \cr} $$