A friend of mine was a contestant with his family, and they came back with a massive list of questions which they were asked to fill in towards the '100 people surveyed', so if you multiply 20 families who enter the heats, and give them a batch of questions each, hey presto - that's your survey done.
They do in fact use previous contestants as the 100 people surveyed. The reguarly send out questions to previous people and thats how they get "100 people we asked"
i dont know anyone that has been asked but i remember watching it once and the question was "name something to do with the story little red riding hood"and one of the family members said a witch which is wrong but it was on the board as 1 of the answers there must have been a number of people that gave that answer.so it just goes to show you even a wrong answer can get on the board.