How many $km/h$ does a man walk who passes through a street $600 \, m$ long in $5 \, minutes$?

$A$ man takes $6\, h \, 15\, min$ in walking a distance and riding back to the starting place. He could walk both ways in $7\, h \, 45\, min$. The time taken by him to ride both ways is:

$A$ man travels $600 \, km$ by train at $80 \, km/hr$, $800 \, km$ by ship at $40 \, km/hr$, $500 \, km$ by aeroplane at $400 \, km/hr$, and $100 \, km$ by car at $50 \, km/hr$. What is the average speed for the entire distance? (in $km/hr$)

$A$ 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:

$A$ boy rides his bicycle $10 \, km$ at an average speed of $12 \, km/hr$ and again travels $12 \, km$ at an average speed of $10 \, km/hr$. His average speed for the entire trip is approximately (in $km/hr$)

$A$ train travelling with a speed of $60 \, km/h$ catches another train travelling in the same direction and then leaves it $120 \, m$ behind in $18 \, seconds$. The speed of the second train is (in $km/h$):