A train moves towards a stationary observer with speed `34 m//s`. The train sound a whistle and its frequency registered by the observer 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

Options

A. `(18)/(19)`
B. `(1)/(2)`
C. 2
D. `(19)/(18)`

Answer

C

Explanation

`f_1=((340)/(340-34))f=(10)/(9)f`
`f_2=((340)/(340-17))f=(20)/(19)f`
`(f_1)/(f_2)=((10)/(9))/((20)/(19))=(19)/(18)`