Shirts numbered consecutively from 1 to 20 are worn by 20 members of a bowling league. While any three of these members are selected to be a team, the league aims to use the sum of their shirt numbers as the code number for the team. Display that if any eight of the 20 are chosen, after that from these eight one may form at least two different teams having similar code number

Ans: While a team containing three persons is selected and number inscribed on the shirt is added, the possible minimum number is (1+ 2 + 3 =) 6 and the maximum number is (18 + 19 + 20 =) 57.  So a team of three can have a code number from the possible range of 52 codes from 6 to 57 both inclusive. Now after selecting 8 from 20 members, any three out of 8 can be selected in

⁸C₃ = 56. 

Now using the Pigeon Hole principle, let 56 pigeons are placed into 52 holes marked with codes between 6 and 57, then there are at least two teams will be in the same hole, implying that these two teams will have the same code number.