$A$ man leaves a point $P$ and reaches the point $Q$ in $4 \, hours$. Another man leaves the point $Q$,$2 \, hours$ earlier and reaches the point $P$ in $4 \, hours$. Find the time in which the first man meets the second man (in $hours$).

$A$ train crosses a pole in $10 \, s$ and a platform,which is $40 \%$ longer than the length of the train,in $24 \, s$. If the length of the platform is $140 \, m$,what is the speed of the train in $m/s$?

$A$ train can travel $50\%$ faster than a bus. Both start from point $A$ at the same time and reach point $B$ at the same time. Point $B$ is $75 \, km$ away from point $A$. On the way, the train stops for $12.5 \, minutes$. The speed of the bus is (in $km/h$):

Buses start from a bus terminal with a speed of $20 \text{ km/h}$ at intervals of $10 \text{ mins}$. What is the speed of a man coming from the opposite direction towards the bus terminal if he meets the buses at intervals of $8 \text{ mins}$? (in $\text{km/h}$)

Two trains start at the same time from Delhi and Mumbai and move towards each other at the rate of $85 \, km/h$ and $65 \, km/h$ respectively. When they meet,it is found that one train has travelled $20 \, km$ more than the other. Find the distance between Delhi and Mumbai (in $km$).

$A$ thief is noticed by a policeman from a distance of $200\, m$. The thief starts running and the policeman chases him. The thief and the policeman run at the rate of $10\, km/h$ and $11\, km/h$ respectively. What is the distance between them after $6\, minutes$? (in $m$)