Answer to Question #50144 in Combinatorics | Number Theory for Quamrul

Question

3 buses have to cross a long bridge, and it is so narrow that a bus cannot overtake another. The buses can
have only integer-number-velocities ranging from 10ms-1
to 20ms-1
and no two buses can have the same
speed. How many ways the velocities can be distributed among the buses so that they can cross the
bridge without any accident?