$A$ man goes from a place $A$ to $B$ at a speed of $12 \, km/hr$ and returns from $B$ to $A$ at a speed of $18 \, km/hr$. The average speed for the whole journey is (in $km/hr$):

The ratio of the speed of a bus to that of a train is $15: 27$. Also,a car covered a distance of $720 \text{ km}$ in $9 \text{ hours}$. The speed of the bus is $\frac{3}{4}$ the speed of the car. How much distance will the train cover in $7 \text{ hours}$? (in $\text{km}$)

In covering a certain distance,the speeds of $A$ and $B$ are in the ratio of $3:4$. $A$ takes $30 \text{ minutes}$ more than $B$ to reach the destination. The time taken by $A$ to reach the destination is (in $\text{hours}$):

$A$ person has to travel from point $A$ to point $B$ in a certain time. Travelling at a speed of $5 \, km/h$,he reaches $48 \, min$ late,and while travelling at a speed of $8 \, km/h$,he reaches $15 \, min$ early. What is the distance from point $A$ to $B$ (in $km$)?

Train $A$ starts its journey from Patna to Hazipur while train $B$ starts from Hazipur to Patna. After crossing each other, they finish their journey in $81\, \text{hours}$ and $121\, \text{hours}$ respectively. What will be the speed of train $B$ if the speed of train $A$ is $44\, \text{km/h}$?

$A$ train completes a non-stop journey in $8 \, \text{hours}$. If it had travelled $5 \, \text{km/h}$ faster, it would have completed the journey in $6 \, \text{hours} \, 40 \, \text{minutes}$. What is its lowest speed in $\text{km/h}$?