Ahigh school principal wants to test the overall mood in his school. he stops the first fifteen students who come into the office one morning and asks them to rate their high school experience on a scale of 1 (worst) to 10 (best). the average response is 3.2, and the principal concludes that his school's mood is poor.
the principal's conclusion
a) is based on too small a sample.
b) is valid, since the students were chosen randomly.
c) is unfair, since he is the one running the school.
d) is invalid, since the students were chosen by convenience.