Permutations and Combinations
Everybody in a function shakes hand with everybody else. The total number of handshakes are 45. Find the number of persons in the function.
Solution: Let there be people in the function.
We name the people as
Take person 1: He can shake hands with people.
Take person 2: He can shake hands with people.
Take person : He can shake hands with 1 people.
Adding them together:
There were 10 people in the party.