If a train runs at $40 \text{ km/h}$,it reaches its destination late by $11 \text{ minutes}$,but if it runs at $50 \text{ km/h}$,it is late by $5 \text{ minutes}$ only. Find the correct time for the train to complete its journey (in minutes).

$A$ person goes from point $A$ to $B$ with a speed of $55 \text{ km/hr}$ and returns with a speed of $65 \text{ km/hr}$. What is the average speed (in $\text{km/hr}$) of the person while going and coming back from $A$ to $B$?

Walking $\frac{6}{7}$ of his usual speed, a man is $12 \, \text{minutes}$ late. The usual time taken by him to cover that distance is

Two trains of lengths $120 \,m$ and $80 \,m$ are running in the same direction with velocities of $40 \,km/h$ and $50 \,km/h$ respectively. The time taken by them to cross each other is (in $sec$).

$A$ bus travels $720 \text{ km}$ in $20 \text{ hours}$. Calculate its average speed in $\text{metres/seconds}$.

Two places $P$ and $Q$ are $162 \, km$ apart. $A$ train leaves $P$ for $Q$ and simultaneously another train leaves $Q$ for $P$. They meet at the end of $6 \, hours$. If the former train travels $8 \, km/h$ faster than the other,then the speed of the train from $Q$ is (in $km/h$):