$A$ boy goes to his school from his house at a speed of $3 \, km/hr$ and returns at a speed of $2 \, km/hr$. If he takes $5 \, hours$ in total for the round trip,the distance between his house and school is (in $km$):

$A$ horse rider travels on horseback from Bhopal to Chandigarh at a constant speed. If the horse increased its speed by $6 \, km/h$,it would take the rider $4 \, hours$ less to cover that distance. If the horse travelled at a speed $6 \, km/h$ lower than the initial speed,it would take him $10 \, hours$ more than the time he would have taken if he had travelled at a speed $6 \, km/h$ higher than the initial speed. Find the distance between Bhopal and Chandigarh in $km$.

$A$ thief is stopped by a policeman from a distance of $150\, m$. When the policeman starts the chase,the thief also starts running. Assuming the speed of the thief as $7\, km/h$ and that of the policeman as $9\, km/h$,how far would the thief have run before he is overtaken by the policeman? (in $m$)

Two trains,$130 \,m$ and $110 \,m$ long,are moving in the same direction. The faster train takes $1 \,minute$ to pass the other completely. If they are moving in opposite directions,they pass each other completely in $3 \,seconds$. Find the speed of each train (in $m/s$).

Two cars $A$ and $B$ travel from one city to another,at speeds of $72\, km/hr$ and $90\, km/hr$ respectively. If car $B$ takes $1\, hour$ less than car $A$ for the journey,what is the distance (in $km$) between the two cities?

How many seconds will a $500 \, m$ long train take to cross a man walking with a speed of $3 \, km/h$ in the direction of the moving train, if the speed of the train is $63 \, km/h$?