In many cities in the southwestern part of the US, water is being withdrawn from subsurface aquifers faster than it is being replaced. The groundwater depletion has forced some cities to take action to encourage water conservation. Beginning in the mid1990s, a city undertook a project to encourage installation of ultralowflush toilets in existing houses. The toilet replacement program involved a rebate of 75% of the cost of the fixture (up to $100 per unit), providing the toilet used no more than 1.6 gallons of water per flush. In the twelve months before and after installation, the water consumption was monitored during the months of December, January and February. A total of 268 residences were monitored. Monthly consumption before and after installation was found to be 11.2 and 9.1 CCF respectively, resulting in a water savings rate of 18.8%. During the first 2 years of the program, the average cost of a toilet was $115.83 and the average rebate was $76.12. a. Determine the simple payback, and the payback period assuming an interest rate of 5%. Assume installation costs $50, the water charge is $0.76 per CCF and the sewer surcharge is $0.62 per CCF. b. If the toilet has a productive life of 5 years, is the toilet replacement program cost effective for the city?