A siren placed at a railway platform is emitting sound of frequency `5 kHz`. A passenger sitting in a moving train `A` records a frequency of `5.5kHz` while the train approaches the siren. During his return journey in a different train `B` he records a frequency of `6.0 kHz` while approaching the same siren. the ratio the velocity of train `B` to that of train `A` is

Options

A. `242//252`
B. `2`
C. `3`
D. `11//6`

Explanation

`n'=n((V+V_(e))/(V))`
`n'V=nV+nV_(o)`
`V((n'-n))/n=Ve`
`V_(o)prop(n'-n)`
`(V_(2))/(V_(1))=(6.5-5)/(5.5-5)=3`