Suppose you are a statistics consultant, hired to study whether a tax on alcohol has decreased average alcohol consumption in Australia. For a given sample of randomly selected individuals, you are able to obtain the difference in alcohol consumption (in litres) for the years before and after the tax. For person i, who is randomly sampled from the population, Yi denotes the change in alcohol consumption. Suppose that your sample size is n = 900 and you obtain the sample mean y = -0.97 and sample standard deviation s = 13.8. a. State the null and alternative hypotheses and explain the type of test you will conduct.