$A$ train runs at an average speed of $75\, km/hr$. If the distance to be covered is $1050\, km$, how long will the train take to cover it? (in $hrs$)

$A$ car travels the first one-third of a certain distance with a speed of $10\, km/hr$,the next one-third distance with a speed of $20\, km/hr$,and the last one-third distance with a speed of $60\, km/hr$. The average speed of the car for the whole journey is (in $km/hr$):

$A$ train of length $100\, m$ crosses another train of length $150\, m,$ running on a parallel track in the opposite direction in $9\, s.$ If the speed of the train having length $150\, m$ is $40\, km/h,$ what is the speed (in $km/h$) of the other train?

$A$ train $300 \text{ m}$ long is running at a speed of $90 \text{ km/h}$. How many seconds will it take to cross a $200 \text{ m}$ long train running in the opposite direction at a speed of $60 \text{ km/h}$?

$A$ person has to cover a distance of $6 \, km$ in $45 \, minutes$. If he covers one-half of the distance in two-third of the total time,to cover the remaining distance in the remaining time,his speed (in $km/hr$) must be:

In a race of $800\, m,$ $A$ can beat $B$ by $40\, m$. In a race of $500\, m,$ $B$ can beat $C$ by $5\, m$. In a race of $200\, m,$ $A$ will beat $C$ by? (in $m$)