With decreased natural fuel supplies and rising costs, in recent years more and more car manufacturers are switching to hybrid technology. The traditional vehicles draw power from either a gas or diesel engine. Hybrids, however, draw power from two energy sources, typically a gas or diesel engine combined with an electric motor. General Motors developed a hybrid technology that is used in mass-transit vehicles in Seattle. Although more fuel efficient, hybrid technology is also more expensive. Another city in the United States is considering switching to hybrid masstransit vehicles and would like to compare fuel economy as well as emissions by traditional and hybrid mass-transit vehicles. Design a study to help them make a decision.