Which of the following statements is false?

$A$ train moving towards a hill at a speed of $72\ km/hr$ sounds a whistle of frequency $500\ Hz$. $A$ wind is blowing from the hill at a speed of $36\ km/hr$. If the speed of sound in air is $340\ m/s$,the frequency heard by a man on the hill (nearly) is ... $Hz$

An engine sounding a whistle of frequency $2000 \,Hz$ is receding from a stationary observer at $72 \,km/h$. What is the apparent frequency heard by the observer (in $\,Hz$)? The velocity of sound in air is $340 \,m/s$.

$A$ motorcyclist is moving around a circular track of radius $50 \ m$ with a constant speed of $25 \ m/s$. $A$ static siren at point $Y$ emits sound of frequency $n$. How many times (approximately) in an hour will the motorcyclist hear the sound of the actual frequency $n$?

An audio transmitter $(T)$ and a receiver $(R)$ are hung vertically from two identical massless strings of length $8 \ m$ with their pivots well separated along the $X$ axis. They are pulled from the equilibrium position in opposite directions along the $X$ axis by a small angular amplitude $\theta_0 = \cos^{-1}(0.9)$ and released simultaneously. If the natural frequency of the transmitter is $660 \ Hz$ and the speed of sound in air is $330 \ m/s$,the maximum variation in the frequency (in $Hz$) as measured by the receiver (Take the acceleration due to gravity $g = 10 \ m/s^2$) is:

$A$ train,standing at the outer signal of a railway station,blows a whistle of frequency $400\; Hz$ in still air.
$(i)$ What is the frequency of the whistle for a platform observer when the train $(a)$ approaches the platform with a speed of $10\; m s^{-1}$,$(b)$ recedes from the platform with a speed of $10\; m s^{-1}$?
$(ii)$ What is the speed of sound in each case? The speed of sound in still air can be taken as $340\; m s^{-1}$.