Chapter 11, Problem 51E

Dowsing Before drilling for water, many rural homeowners hire a dowser (a person who claims to be able to sense the presence of underground water using a forked stick). Suppose we wish to set up an experiment to test one dowser’s ability. We get 20 identical containers, fill some with water, and ask him to tell which ones they are.

1. a) How will we randomize this procedure?
2. b) The dowser correctly identifies the contents of 12 out of 20 containers. Do you think this level of success is statistically significant? Explain.
3. c) How many correct identifications (out of 20) would the dowser have to make to convince you that the forked-stick trick works? Explain.