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 consisting of 100 homes.
The builders installed more efficient water fixtures, such as low- flush toilets, and subsequently conducted a survey of the residences. Thirty-six homes responded, and the sample mean water use per day was 64 gallons with a standard deviation of 8.8 gallons per day.
At the .10 level of significance, is that enough evidence to conclude that residents of Legacy Ranch use less water on average?