In the above example it is possible that ten persons...

In the above example it is possible that ten persons conspire to say that they have heard the particular report from the radio. Even 200 persons may combine. But there are cases in which there is no such possibility. For example, you go to South Africa and find a person saying that the radio has broadcast such and such report. Then you go to East Africa and again find some persons reporting the same thing. Then you go to West Africa and the same story is repeated.