Question 26
A bus, a train and a plane leave at the same time from the city $A$ to the city $B$. If I take the bus whose average speed is $100~\mathrm{km}/\mathrm{h}$, I will arrive at $B$ city at 8 pm. If I take the train, whose average speed is $300~\mathrm{km}/\mathrm{h}$, I will arrive at the city $B$ at 2 pm. What will be the plane's arrival time if its average speed is $900~\mathrm{km}/\mathrm{h}$?