$A$ person has to reach a certain place at a certain time. He finds that he will be $15 \text{ minutes}$ late if he walks at $4 \text{ km/h}$,and $10 \text{ minutes}$ earlier if he walks at $6 \text{ km/h}$. How far has he to walk? (in $\text{km}$)

$A$ boy walking at a speed of $10\, km/hr$ reaches his school $15\, minutes$ late. Next time he increases his speed by $2\, km/hr$, but still he is late by $5\, minutes$. Find the distance of his school from his house (in $km$).

$A$ man walking at $3 \, km/h$ crosses a square field diagonally in $2 \, minutes$. The area of the field (in $m^2$) is:

Train $A$ crosses a pole in $25 \text{ seconds}$ and another Train $B$ crosses a pole in $1 \text{ minute}$ and $15 \text{ seconds}$. The length of Train $A$ is half the length of Train $B$. What is the respective ratio between the speeds of Train $A$ and Train $B$?

$A$ 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 $50\, m$ long passes a platform $100\, m$ long in $10\, s$. The speed of the train in $m/s$ is: