$A$ $280 \, m$ long train moving with an average speed of $108 \, km/h$ crosses a platform in $12 \, seconds$. $A$ boy crosses the same platform in $10 \, seconds$. What is the speed of the boy in $m/s$?

$A$ speed of $45\, km/h$ is equivalent to which speed in $m/s$?

An athlete runs a $200$ $\text{meters}$ race in $24$ $\text{seconds}$. His speed is (in $\text{km/hr}$):

Two guns were fired from the same place at an interval of $13 \text{ minutes}$,but a person in a train approaching the place hears the second shot $12 \text{ minutes } 30 \text{ seconds}$ after the first. Find the speed of the train,assuming that sound travels at $330 \text{ m/s}$ (in $\text{km/hr}$).

$A$ thief is spotted by a policeman from a distance of $200 \text{ meters}$. When the policeman starts to chase the thief,the thief also starts running. Assuming the speed of the thief is $10 \text{ km/h}$ and that of the policeman is $12 \text{ km/h}$,how far will the thief have run before he is overtaken by the policeman? (in $\text{km}$)

$A$ cyclist,after cycling a distance of $70 \,km$ on the second day,finds that the ratio of distance covered by him on the first two days is $4:5$. If he travels a distance of $42 \,km$ on the third day,then the ratio of distances travelled on the third day and the first day is: