The speed of a train going from Nagpur to Allahabad is $100 \text{ km/h}$,while its speed is $150 \text{ km/h}$ when coming back from Allahabad to Nagpur. What is the average speed during the whole journey in $\text{km/h}$?

$A$ train leaves the station $1 \, hr$ before the scheduled time. The driver decreases its speed by $4 \, km/hr$. At the next station $120 \, km$ away,the train reaches on time. Find the original speed of the train in $km/hr$.

Two trains,$A$ and $B,$ start from stations $X$ and $Y$ towards $Y$ and $X$ respectively. After passing each other,they take $4\, \text{hours } 48\, \text{minutes}$ and $3\, \text{hours } 20\, \text{minutes}$ to reach $Y$ and $X$ respectively. If train $A$ is moving at $45\, \text{km/h},$ then the speed of train $B$ is (in $\text{km/h}$)

Excluding stoppages, the speed of a bus is $54 \, km/h$ and including stoppages, it is $45 \, km/h$. For how many minutes does the bus stop per hour?

Two cars $P$ and $Q$ start at the same time from $A$ and $B$ which are $120 \, km$ apart. If the two cars travel in opposite directions,they meet after $1 \, hour$,and if they travel in the same direction (from $A$ towards $B$),then $P$ meets $Q$ after $6 \, hours$. What is the speed of car $P$ (in $km/hr$)?

$A$ $110 \text{ meters}$ long train passes a man walking at the speed of $6 \text{ km/h}$ against it in $6 \text{ seconds}$. The speed of the train in $\text{km/h}$ is: