There are 18 stations between Hyderabad and Bangalore. How many second class tickets have to be printed, so that a passenger can travel from any station to any other station?
Choose the correct choice.
A) 200  B) 220  C) 380  D) 240  E) 250
Explanation:   The total number of stations = 20   From 20 stations we have to choose any two stations and the direction of travel (i.e., Hyderabad to Bangalore is different from Bangalore to Hyderabad) in ²⁰P₂ ways.   ²⁰P₂ = 20 * 19= 
<gadget id="calculator">20 * 19</gadget>
<output>380</output>
380   380
<result>C</result>
There are 18 stations between Hyderabad and Bangalore. How many second class tickets have to be printed, so that a passenger can travel from any station to any other station?