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 $\text{km/h}$?

Two places $A$ and $B$ are $100 \, km$ apart on a highway. One car starts from $A$ and another from $B$ at the same time. If the cars travel in the same direction at a constant speed,they meet in $5 \, hours$. If the cars travel towards each other,they meet in $1 \, hour$. What is the speed of the car running faster? (in $km/h$)

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 $m$)

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 $45 \, km/h$?

$A$ 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 $km/hr$.

$A$ train $110 \, m$ long is running with a speed of $60 \, km/h$. In what time will it pass a man who is running at $6 \, km/h$ in the direction opposite to that in which the train is going? (in $seconds$)