Supposing that telegraph poles on a railroad are $50 \, m$ apart,how many will be passed by a train in $4 \, hours$ if the speed of the train is $45 \, km/h$?

Two trains are running in opposite directions with the same speed. If the length of each train is $135 \, m$ and they cross each other in $18 \, s$,the speed of each train is (in $km/h$):

The diameter of each wheel of a car is $70 \, cm$. If each wheel rotates $400 \, \text{times per minute}$, then the speed of the car (in $km/hr$) is $\left( \text{Take } \pi = \frac{22}{7} \right)$.

The average speed of a car is $1 \frac{4}{5}$ times the average speed of a bus. $A$ tractor covers $575 \text{ km}$ in $23 \text{ hours}$. How much distance will the car cover in $4 \text{ hours}$ if the speed of the bus is twice the speed of the tractor? (in $\text{km}$)

What is the length of the bridge (in $m$) that a man riding at $15 \, km/h$ can cross in $5 \, minutes$?

$A$ passenger train running at the speed of $80 \text{ km/h}$ leaves the railway station $6 \text{ hours}$ after a goods train leaves and overtakes it in $4 \text{ hours}$. What is the speed of the goods train? (in $\text{km/h}$)