Question

a sociologist is investigating the spread of a rumor. he finds that 20 people know of the rumor. one of these people must have started the rumor, and each must have heard the rumor for the first time from one of the others. he draws a graph with vertices representing the 20 people and edges showing whom each person first heard the rumor.treenot necessarily a tree

Answer 1

This graph will be a tree.

This is because the rumor must have started from one person