The American Water Works Association reports that the per capita water use in a single-family home is 69 gallons per day. Legacy Ranch is a relatively new housing development. The builders installed more efficient water fixtures, such as low-flush toilets, and subsequently conducted a survey of the residences. Twenty-five owners responded, and the sample mean water use per day was 64 gallons with a standard deviation of 7.1 gallons per day. At the 0.10 level of significance, is that enough evidence to conclude that residents of Legacy Ranch use less water on average? a) What is the decision rule?
b) The value of the test statistic is:__.