In a network of railways, a small island has 15 stations. Find the number of different types of tickets to be printed for each class, if every stations must have tickets for other stations.

On a railway route there are 20 stations. What is the number of different tickets required in order that it may be possible to travel from every station to every other station

There are 10 railway stations between a station X and another station Y. Find the number of different tickets that must be printed so as to enable a passenger to travel from one station to any other.

On a railway there are 20 stations. The number of different tickets required in order that it may be possible to travel from every station to every station is :

On a railway there are 20 stations. The number of different tickets required in order that it may be possible to travel from every station to every station is

On a railway there are 20 stations. The number of different tickets required in order that it may be possible to travel from every station to every station is

On a railway there are 20 stations. The number of different tickets required in order that it may be possible to travel from every station to every station is

On a railway there are 10 stations. The number of types of tickets required in order that it may be possible to book a passenger from every station to every other is

On a raiway there are 10 stations. The number of types of tickets required in order that it may be possible to book a passenger from every staton to every other is

On a railway there are 20 stations.The number of different tickets required in order that it may be possible to travel from every station to every station is