A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is ${{f}_{1}}$. If the train’s speed is reduced to 17 m/s, the frequency registered is ${{f}_{2}}$. If the speed of sound is 340 m/s then the ratio ${{f}_{1}}/{{f}_{2}}$ is