A cereal manufacturer claims that 10% of its cereal boxes contain a free ticket to the movies. Because you have eaten several boxes of cereal without finding a movie ticket, you are suspicious of this claim. You set up a website to ask people about their experience with the cereal boxes. Once you have 250 responses, you shut the website down, and do some calculations. You discover that 20 of your 250 respondents have found free movie tickets. Do you have a case against the manufacturer's claim? (Is this really a random sample? Why or why not? What do you have to think about in order to answer this question?)