$A$ person covers a certain distance in $6 \, hours$ if he travels at $40 \, km/h$. If he has to cover the same distance in $4 \, hours$,then his speed must be (in $km/h$):

$A$ man crosses a stationary bus in $18\, s$. The same bus crosses a pole in $4\, s$. What is the ratio of the speed of the bus to the speed of the man?

$A$ and $B$ run a kilometer and $A$ wins by $25 \text{ sec}$. $A$ and $C$ run a kilometer and $A$ wins by $275 \text{ m}$. When $B$ and $C$ run the same distance,$B$ wins by $30 \text{ sec}$. The time taken by $A$ to run a kilometer is

Anna left for city $A$ from city $B$ at $5:20\, a.m.$ She travelled at a speed of $80\, km/h$ for $2\, hours\, 15\, minutes.$ After that,the speed was reduced to $60\, km/h.$ If the total distance between the two cities is $350\, km,$ at what time did Anna reach city $A$?

$A$ carriage driving in a fog passed a man who was walking at the rate of $3 \text{ km/h}$ in the same direction. He could see the carriage for $4 \text{ minutes}$ and it was visible to him up to a distance of $100 \text{ m}$. What was the speed of the carriage in $\text{km/h}$?

Train $A$ crosses a stationary Train $B$ in $50 \,s$ and a pole in $20 \,s$ with the same speed. The length of Train $A$ is $240 \,m$. What is the length of the stationary Train $B$ (in $m$)?