For which of the following claims is a representative sample, rather than a biased sample, likely to be essential? For which would a biased sample be acceptable? EXPLAIN your answers!

1.A political poll predicting who will win a governor's race

2.Online readers' ratings of a recently released film

3.Estimating school achievement from a sample of test scores from 10 district schools, in order to evaluate which of the 10 schools is the highest achieving

4.Evaluating the quality of the day's surfing conditions by asking surfers on the local beach