Two whistles $A$ and $B$ each have a frequency of $500\,\,Hz$. $A$ is stationary and $B$ is moving towards the right (away from $A$) at a speed of $50\,\, m/s$. An observer is between the two whistles moving towards the right with a speed of $25\,\, m/s.$ The velocity of sound in air is $350 \,\,m/s$. Assume there is no wind. Then which of the following statements are true:
  • AThe apparent frequency of whistle $B$ as heard by $A$ is $444\,\,Hz$ approximately
  • BThe apparent frequency of whistle $B$ as heard by the observer is $469\,\,Hz$ approximately
  • CThe difference in the apparent frequencies of $A$ and $B$ as heard by the observer is $4.5 \,\,Hz.$
  • Dboth $(B)$ and $(C)$
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