Amigo Mobility, which manufactures battery-powered mobility scooters, has $670,000 to invest. The company is considering three different battery projects that will yield the following rates of return:

Deep cycle = 15% Wet/flooded = 36% Lithium ion = 23%

The initial investment required for each project is $ 170,000, $100,000, and $400,000, respectively. If Amigo's invests in all three projects, what will be its overall rate of return?