A research firm wishes to assess the effectiveness of a campaign to reduce household water consumption. Before the campaign, the utility company reported a daily usage of 46 gallons per household. After the advertising campaign, the utility company randomly selects 100 households throughout the region and records water usage for a day? The household average water usage after the campaign was 42.26 gallons with a standard deviation of 6.92 gallons. Using a 95% confidence level, use a hypothesis test for the mean to see if the average household water usage after the campaign decreased.

a. State your null and alternate hypotheses. Is this a one-sided or two-sided test?

b. What is your significance level? What does this mean in terms of risk of error?

c. Draw your critical region. What is the critical value of the test statistic? Write a decision rule based on this critical value of the test statistic.

d. Based on the sample results, compute the test statistic.

e. Determine the p-value for the sample mean value. Interpret this value. Write a decision rule based on c. and the p-value.

f. State your conclusion regarding the null hypothesis.