Answer:
A radio station chose 1000 at random within its broadcast area. It sent a survey to be filled out that asked questions about radio habits.
There can be two major problems here.
1. Lets suppose 30% people listen to radio, so we can say that the information gathered through the survey cannot be accurate.
2. The survey was a self filled survey, means people self filled out the questions, so there is a possibility that people may not be honest while answering.